Big money flows into 10 battleground Senate races as GOP defends its majority

With less than two months to the crucial November election, a handful of battleground Senate races have captured an outsized share of campaign cash in the 2018 midterm cycle.

As of mid-September, roughly 40 percent of the more than half a billion dollars in direct contributions raised by Senate candidates had flowed into just 10 races. They include contests for open seats in Arizona and Tennessee. The rest are for races in which incumbents are defending seats: in Florida, Indiana, Missouri, Montana, Nevada, North Dakota, Texas and West Virginia.

And some 70 percent of the $185 million in spending by outside groups had gone to the same 10 of the 35 senate races in the 2018 cycle, according to a CNBC analysis of data from the Center for Responsive Politics.

That so-called soft money comes in the form of independent expenditures that aren't limited by campaign finance regulations. Also known as outside spending — funds favoring one party or another without coordinating directly with a candidate — the method has become the preferred conduit for campaign contributions. It totaled roughly $1.4 billion in the 2016 election cycle.

As of the end of the first quarter, overall independent expenditures amounted to about $88 million, according to the Center for Responsive Politics. By mid-September, that amount had more than tripled to more than $300 million. (Those figures don't include so-called dark money contributions, which are not required to be reported to the Federal Election Commission.)

It remains to be seen how much more of this soft money will be spent in the 2018 cycle. By the same point in the 2010 midterms, only 25 percent of the total in that cycle had been spent. In the 2014 midterms, that share of money raised by mid-September rose to 35 percent of the total.

As Republicans battle to keep control of their one-vote majority in the Senate, most of the 35 seats up for election in November are the Democrats' to lose: The GOP defends just nine of those 35 seats. Of the 10 races widely considered most competitive competitive, Republicans hold four.

Five Democrats face re-election in states President Donald Trump won overwhelmingly in 2016. Only one Republican — Sen. Dean Heller of Nevada — is running in a state that Democrat Hillary Clinton carried.

Democrats face tough path to majority

Pundits largely see Democrats as favorites to win back control of the House but as underdogs in winning back the Senate. To take a Senate majority, the party has to net two seats in November.

While flipping the Senate appears daunting for Democrats, the party does have a path to do so. It would require winning eight of the 10 battleground races considered most competitive. For example, if only one incumbent Democrat loses, the party would have to defend all its other seats and flip three GOP-held seats to take a majority.

If Republicans knock out two Democratic senators, it all but assures them they will keep their majority, unless Democrats can pull off a nearly clean sweep of accessible Republican seats.

Earlier this week, Senate Majority Leader Mitch McConnell described the 10 races listed above — excluding Texas — "too close to call and every one of them like a knife fight in an alley, just a brawl." He separately called the Texas race between Republican Sen. Ted Cruz and Democrat Beto O'Rourke "competitive."

To put a figure on it, models made by widely followed data guru Nate Silver's FiveThirtyEight give Democrats about a 1-in-3 chance of taking the Senate. The average projected outcome leaves the Senate right about where it started, with the GOP holding a 51-49 majority.

In assessing the potential outcomes, Silver writes that "just as Republicans are far from doomed in the House, they are far from safe in the Senate." Still, the site's models see a Democratic House and a Republican Senate as the most likely scenario after November's elections.

A number of factors, including Trump's approval rating, the congressional generic ballot and the money that flows into each of the contests, could change the likelihood of the Senate flipping between now and November. In addition, a handful of races for seats not outlined here could become more competitive.

Here are the key races to watch:

Arizona

Two members of Congress vie to replace outgoing Republican Sen. Jeff Flake in Arizona, one of the Democrats' best pickup opportunities this year.

Rep. Martha McSally will try to keep the seat red in a fight with Democratic Rep. Kyrsten Sinema.

Trump won the state by about 5 percentage points in 2016. The race to fill Flake's seat is a dead heat, with an average of recent polls finding a slight edge for Sinema, according to RealClearPolitics.

Florida

Longtime Democratic Sen. Bill Nelson aims to defend his seat amid the toughest challenge he has ever faced. He will try to hold off Republican Gov. Rick Scott, a well-funded challenger with statewide name recognition.

Trump only narrowly carried Florida in 2016. But Scott's wealth and role as governor appear to be at least partially canceling a boost Nelson would get from high Democratic enthusiasm this year.

An average of recent polls has shown the contest in a dead heat, with Scott at a slight advantage, according to RealClearPolitics. Candidates and outside groups have poured money into the Florida race, making it this year's most expensive Senate contest.

Indiana

First-term Democratic Sen. Joe Donnelly tries to earn re-election in a state where Trump breezed to victory in 2016. The president has jabbed Donnelly repeatedly as he aims to boost Republican Mike Braun, dubbing the senator "Sleepin' Joe."

To keep his seat in Vice President Mike Pence's home state, the Democrat has tried to boost his bipartisan credentials. He has touted his votes for Trump's immigration proposal and nominees for key posts, while highlighting his efforts with Democrats to protect pre-existing condition coverage under the Affordable Care Act.

Braun, a businessman and former state lawmaker, has cast himself as a job creator who will support Trump's agenda. Recent polls have shown an edge for Donnelly in one of Republicans' top Senate targets this year.

Missouri

In another key GOP target, Democratic Sen. Claire McCaskill hopes to hold off Missouri Attorney General Josh Hawley. Trump carried the state by nearly 20 percentage points in 2016. McCaskill has one of the most difficult paths to re-election of any senator.

Like most of her colleagues in difficult races, McCaskill has emphasized health care as her top priority. She has also tried to build a centrist, bipartisan brand as she pushes to keep her seat.

Hawley, who has Trump's endorsement, has aimed to cast McCaskill as a wealthy and out of touch career politician. Polls suggest the Missouri race is a dead heat.

Montana

Democratic Sen. Jon Tester faces Republican Montana Auditor Matt Rosendale as he seeks his third term in office. Tester, while personally popular in his state, faces a difficult task in trying to defend a seat in a state Trump won by about 20 percentage points in 2016.

Tester, like his red-state colleagues, has promoted his record of voting with Trump more often than most of his Democratic colleagues. Still, he has broken with Trump on several issues, most notably by opposing Supreme Court Justice Neil Gorsuch as several Democrats running in Trump states supported the judge.

Rosendale, who has received Trump's endorsement, has attacked Tester as an entrenched Washington official too beholden to lobbyists. Trump has directed venom at the senator for his role in the president's past choice to run the Department of Veterans Affairs, Dr. Ronny Jackson, withdrawing from consideration for the job.

While polling has been limited, Tester appears to have an edge so far.

Nevada

In Nevada, Democrats have their best chance to knock off a Senate GOP incumbent. Heller will try to defeat Democratic Rep. Jacky Rosen in a state Clinton won by more than 2 percentage points in 2016.

Heller notably opposed efforts to repeal the Affordable Care Act early last year, before joining in his party's efforts to roll back the health care law. Rosen and national Democrats have repeatedly criticized the Republican senator for that move.

Polling so far shows a tight race in Nevada, with Rosen holding a small advantage.

North Dakota

Trump won North Dakota by more than 30 points in 2016, putting Democratic Sen. Heidi Heitkamp in one of the toughest spots of any Senate incumbent. She faces a tough opponent in GOP Rep. Kevin Cramer.

The senator, like some of her colleagues, has promoted her votes with Trump's priorities, particularly on a bill to ease financial regulations that she championed. Conversely, she has defended the Affordable Care Act and joined some of her farm-state colleagues in criticizing Trump's mounting trade conflicts with key partners.

Cramer, considered Republicans' top recruit to take down Heitkamp, has been one of the most reliable votes for Trump in the House.

Few public polls have surfaced, but those that have been released indicate a dead heat, with a slight edge for Cramer.

Tennessee

Democrats have a surprisingly good chance to flip a Senate seat in red Tennessee as Republican Sen. Bob Corker retires.

Democratic former Gov. Phil Bredesen and GOP Rep. Marsha Blackburn vie to replace the senator. The state has not had a Democratic senator in more than 20 years.

In Bredesen, Democrats have a candidate with statewide name recognition who has pledged to protect health care access but preached fiscal responsibility and promised to work with Republicans where he can. Blackburn has run as an unabashed Trump defender, and has voted with his priorities more than 90 percent of the time. That sets her apart from Corker, a vocal critic of the president.

Recent polls show a close contest that tilts slightly toward Bredesen.

Texas

Democrats hope to shock the country in Texas, a state that the party has not represented in the Senate in 25 years.

Cruz looks to hold off O'Rourke, who has surged in recent polls on the strength of massive fundraising and Democratic enthusiasm. Despite running in a challenging environment in a red state, the Democrat has called for tighter gun control regulations, defended the Affordable Care Act and pushed for a path to citizenship for young immigrants brought to the U.S. illegally as children.

National Republicans have started to pay more attention to Texas as O'Rourke drew closer to Cruz, a first-term senator who came into office as an anti-establishment candidate. Cruz, an immigration hawk, introduced legislation earlier this year meant to end the Trump administration's separation of migrant children from parents at U.S. borders, signaling potential concern about the race.

Still, Cruz appears to have a cushion of a few percentage points as of now. No major independent poll has found a lead for O'Rourke.

West Virginia

Trump triumphed in West Virginia in 2016, carrying the state by about 40 points. While Democratic Sen. Joe Manchin faces a tough environment in the state as he runs for re-election, he appears to be a favorite to keep the seat.

Manchin faces state Attorney General Patrick Morrisey, who has been a staunch defender of Trump and his efforts to roll back environmental regulations.

The Democrat has run as a champion of Obamacare protections and social safety net programs. He has also voted with Trump more often than any of his party colleagues, supporting the president's immigration proposal as well as Gorsuch.

Despite Trump's easy win in West Virginia, the state still has a strong Democratic tradition. It shows in polling: Recent independent surveys have found a comfortable lead for Manchin.

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