California's 49th Congressional District historically has leaned Republican, but Hillary Clinton won it in the 2016 presidential election. Now, with the retirement of GOP Rep. Darrell Issa, the seat is up for grabs. The race is between Republican Diane Harkey, a conservative state official, and environmental lawyer Mike Levin, a Democrat.
Ten weeks before Election Day, recent polling shows the contest remains tight. President Donald Trump weighed in on the race last week by backing Harkey in a move that could be a game changer.
The district includes communities along the Southern California coast from Dana Point in Orange County to Del Mar in San Diego County and is one of nearly two dozen nationwide that Democrats are hoping will help them achieve a blue wave in November. Issa, a 10-term congressman, won re-election in 2016 by only about 1,600 votes and in January announced plans to retire.
Besides taxes, jobs and health care, other top issues seen in the district are immigration, border security and the environment. Several local jurisdictions in the district took a stand against California's so-called sanctuary state laws that seek to protect undocumented immigrants.
There have also been safety concerns over waste storage at the shuttered San Onofre nuclear power plant, which sits on the northern San Diego County coastline. The plant began producing power in the late 1960s, and decommissioning started a few years ago.
Military issues also weigh heavily given the district includes the Camp Pendleton Marine Corps base. Efforts to privatize veterans health care are opposed by both candidates.
Harkey, who served three terms in the state Assembly and is an ex-mayor of Dana Point, is chairwoman of the state Board of Equalization, which oversees the Golden State's taxes. Prior to politics, Harkey worked in banking, first in the 1970s for Security Pacific and later at Bank of America.
Levin, who has never held elected office, is a clean energy advocate and has been involved in federal, state and local campaigns. Besides being an environmental lawyer, he's a former executive director of the Democratic Party of Orange County.
"Clean air and clean water and getting the nuclear waste off our coast ... are not partisan issues," said Levin, who also opposes the Trump administration's plan to rollback environmental emission regulations.
Earlier this month, former President Barack Obama endorsed Levin's candidacy for the seat.
On Monday, Trump endorsed Harkey via a tweet, describing her as "an extraordinary woman of great accomplishment & potential." The president added that she's "strong on crime, loves our Military & Vets-has my total Endorsement!"
"There's good and bad in every president," Harkey said in an interview before the president's endorsement. Harkey said she was "very happy with some of the economic policies" of Trump since they're helping with job creation and allowing people to "keep a little more money in their paycheck."
However, Harkey added, "I will take endorsements but it doesn't mean I follow policies to the tee."
For example, Harkey said she doesn't support the Trump administration's plan to increase offshore drilling. She said if Florida can get an exemption from drilling "so can we."
Yet Harkey believes Trump is doing a good job on immigration and supports the president getting billions to complete the wall along the Mexican border, assuming he makes reforms to the visa system and allows consideration for the Obama era Deferred Action for Childhood Arrivals program. DACA protects immigrants brought unlawfully to the U.S. as children from deportation and provides them work authorization.
Levin, though, is critical of the Trump's immigration policies and what he calls the "family detention fiasco." He believes the Immigration and Customs Enforcement agency "needs serious oversight and a change in its policies," and wants to strengthen border security but considers the president's plan for the wall as "misguided."
It remains to be seen whether Trump's backing will boost Harkey's support among voters. Trump lost the district to Clinton in the 2016 presidential contest by a margin of 7.5 percentage points.
"The 49th is the kind of district that Democrats have been targeting for the last few cycles because of demographic change," said Thad Kousser, chairman of the political science department at the University of California, San Diego. "The district has gotten more Democratic, more Latino and ... these are 'Mitt Romney Republicans more than Donald Trump Republicans."
Democrats need to gain about two dozen seats to take back control of the House. In California, several close races could tip the balance. The 49th is considered one of the closest of those races in California.
Less than 10 minutes after Trump's endorsement, Levin sent out a tweet taking a shot at his GOP opponent: "No surprise that @realDonaldTrump, an expert in failed real estate scams, would endorse my opponent @DianeHarkey, whose campaigns have been funded by a Ponzi Scheme."
The Republican candidate's husband, Dan Harkey, once ran an investment company in Orange County, Point Center Financial. After the 2008 financial crisis, the company fell on hard times and faced a lawsuit from investors.
"In 2008, many people lost everything, and my husband was one of them," Harkey said. She also insisted that she went "through the entire court system and came out cleared by the plaintiffs."
Harkey campaign spokesman Bryan Shroyer on Wednesday responded to Levin's tweet by charging the Democrat "is going to continue to make these false accusations because he doesn't want to talk about the issues."
Harkey has contributed at least $100,000 of her own personal funds for the congressional campaign, although her challenger has raised more money. Levin had about $850,000 in cash on hand as of the latest data while Harkey had less than $200,000.
Regardless, Republicans are hoping the gas tax repeal measure on the November statewide ballot will boost GOP turnout for candidates.
The California Republican Party along with prominent House GOP members, including House Speaker Paul Ryan and House Majority Leader Kevin McCarthy, provided financial support for the gas tax and vehicle fee repeal effort. It follows California's Democratic-led legislature last year approving a bill raising the state excise tax on gasoline by 12 cents per gallon, or a 40 percent increase.
Internal polling by Harkey's campaign showed her up by about 3 percentage points last month, according to Roll Call. Orange County Republican Party Chairman Fred Whitaker suggested last week that that was encouraging given the June primary results when the GOP candidates combined had less than half of the total votes.
Sixteen challengers sought Issa's seat in the June primary. In California's so-called "jungle primary" system, the top two vote-getters, regardless of party affiliation, go on to the general election.
"When we look at how the trend is going, we're very pleased," Whitaker told CNBC. "But we really have to stay on it to drive that turnout. Certainly in the Orange County portion of the district, the gas tax is a huge issue."
A poll conducted June 24-27 by Levin's campaign, meantime, found him with a 3 point advantage over Harkey, according to Roll Call. Parke Skelton, a Levin campaign consultant, Wednesday said "nothing has happened since then to change the numbers. It's close."
— Graphics by CNBC's John Schoen.