Who controls Senate may not be known until January

Midterm election cost: $4 billion

The 2014 midterm elections, a dismal set of races mired in nasty attack ads and largely devoid of serious debate, are thankfully winding toward an end in just over a week. Except they probably aren't.

This columnist just finished a week of interviewing voters and candidates in tight races in North Carolina and Georgia and nothing in those interviews suggested a major wave developing that would wipe out Democrats across the board and install a Republican Senate with a definitive Election Day result.

Instead, voters expressed general disgust with candidates on both sides, although the anger at President Barack Obama and Democrats over the tepid state of the economy tilts the playing field toward the GOP, as I wrote about at greater length in Politico.

Still, a close look at the Senate race map and likely outcomes suggests there is a very good chance we will not know the partisan makeup of the next Senate, and thus the forecast for legislative progress in 2015, until Dec. 7 or possibly Jan. 7, after the new Congress has been sworn in.

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Georgia Democratic candidate Michelle Nunn and Republican candidate David Perdue for U.S. Senate.
Bill Clark | CQ Roll Call | Getty Images

That is because Louisiana, where Democrat Mary Landrieu is trying to hold on, is almost certainly headed to a December runoff. And Georgia, where Democrat Michelle Nunn has a good shot at picking up a GOP-held seat, seems destined for a runoff that, for completely inexplicable reasons, will not take place until Jan. 6, meaning a Christmas time parade of attack ads for lucky Peach State residents.

There is a very good chance we won't know who controls the Senate until those races are completed.

Here is how the Senate landscape is shaping up. Republicans currently have 45 seats in the upper chamber and need a net gain of six to get to 51 to control the upper chamber next year. They are likely to pick up two open seats currently held by Democrats in West Virginia and South Dakota. Polls suggest GOP Rep. Tom Cotton is likely to defeat incumbent Arkansas Sen. Mark Pryor. That would leave the GOP three short of its goal.

Republicans are up in the polls in Alaska and Colorado. Winning those two would leave the magic number at one. But independent Greg Orman, who is likely to caucus with Democrats, could take out incumbent Republican Pat Roberts in Kansas, leaving the GOP two short of a majority.

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Their best opportunities to gain those two come from Iowa, Louisiana, New Hampshire and North Carolina. These races are extremely tough to call but let's say no wave develops and Democrats manage to hold on to New Hampshire and North Carolina while dropping the open seat in Iowa. That would leave Republicans one short of a majority and the race would come down to—you guessed it—Louisiana and Georgia. Republicans would need to take out Landrieu and hold onto the Georgia seat vacated by Sen. Saxby Chambliss to get to 51 and a majority.

In Louisiana, a runoff appears all but guaranteed. Landrieu has a narrow edge in the three-way open primary that takes place on Election Day but is well short of the 50 percent needed to win outright. That would put her in a Dec. 6 runoff against GOP Rep. Bill Cassidy in which she would be a slight underdog. Should Landrieu win that runoff, Democrats in the above scenario would be assured of holding the Senate. But if she loses, which is the more likely outcome, control of the Senate would then likely rest on the outcome of the race in Georgia.

That's because it seems unlikely that either Democrat Michelle Nunn, daughter of popular former Georgia Sen. Sam Nunn, or Republican David Perdue, will get over 50 percent on Election Day. With a third-party candidate in the race, Nunn and Perdue are essentially tied with about 46 percent each in most polls.

If it does go to a runoff, Georgia would in this scenario represent the 51st seat for Republicans and the final firewall for Democrats looking to control 50 seats, which with the Vice President's tie-breaking vote, would give them the majority and keep Sen. Harry Reid in charge for the final two years of Obama's tenure in office.

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That would mean an absolute orgy of outside spending and high-profile campaigning in Georgia in the closing weeks of the year. Every significant 2016 presidential hopeful would likely show up in the state trying to demonstrate electoral power at the dawn of the next political cycle.

Imagine rallies with Bill and Hillary Clinton alongside Nunn and Sen. Rand Paul, Mitt Romney, Jeb Bush and possibly many others showing up for Perdue. This would probably not wind up being the kind of low-profile, low-turnout runoff that would heavily favor Perdue.

There is no guarantee the above scenario plays out. If the GOP has a stronger day than expected on Nov. 4 and runs the table in the true toss-up states, Louisiana and Georgia may not matter. But it is absolutely plausible, and in fact more likely than not, that a weary nation will have to wait until December or even January for the curtain to finally come down on the dismal 2014 midterms.

—By Ben White. White is Politico's chief economic correspondent and a CNBC contributor. He also authors the daily tip sheet Politico Morning Money [politico.com/morningmoney]. Follow him on Twitter @morningmoneyben.