Decide the Senate...

5 keys that will decide control of the Senate

Hillary Clinton's renewed email troubles inject a huge dose of uncertainty into the final days of the volatile fight for the chamber.

By Burgess Everett and Kevin Robillard

Democrats had all the momentum in the brutal battle for the Senate as Donald Trump’s presidential prospects took a nosedive last month. But the sudden relitigation of Hillary Clinton’s email practices has them on defense in the last week of the election, injecting even more uncertainty into the half-dozen races that could go either way and will determine which party controls the Senate.

Simultaneously, Trump has pulled back within striking distance. That makes Democrats nervous not because they think Trump can win, but because many Republican candidates are running ahead of Trump and a small swing in the presidential contest could make the difference in key Senate races.

“Republicans have done a great job of keeping it very close in a bad environment,” said David McIntosh, president of the fiscally conservative Club for Growth, which plowed millions into competitive races. “They’re consistently running anywhere from 5 to 6 points ahead of Trump. If Trump gets within a point or two,” Republicans can hold the chamber.

Democrats are still in the driver’s seat thanks to simple math: Republicans essentially have to run the table in the most competitive races to keep the Senate. Democrats are on offense in North Carolina, Missouri, Indiana, New Hampshire, North Carolina, Florida, Wisconsin and Illinois — and are only on defense in Nevada. That gives them lots of ways to take back the minimum four seats they need, though Democrats are hoping for much greater gains to give them some cushion heading into a brutal 2018 map.

“In terms of Hillary being president. I feel good about where she is. I think people have made their decision,” said Sen. Debbie Stabenow (D-Mich.). “In terms of the Senate, I think it’s tighter. I feel that the odds are we take back the Senate. But the question is, is it taking back the Senate by barely enough seats or [winning] seven or eight seats?”

Here’s POLITICO’s guide to five dynamics to watch in Senate races during what's sure to be a wild final seven days of the campaign.

A November surprise

In interviews on Monday, key strategists from both parties agreed that the “new investigative steps” into Clinton’s email practices announced by FBI Director James Comey are unlikely to seismically shift Senate battlegrounds. But the story is dominating the national news and finally puts the GOP on offense.

Indeed, Republicans spent most of the post-Labor Day period having to respond to the latest Trump outrage — to the point that several GOP candidates unendorsed him. No Democrats are abandoning Clinton after Comey’s bombshell, but at least Republicans have a new message to press.

“These kind of political disturbances, disruptions can have an effect. How much, I think is the question. But in a tight race, it could be significant,” said Sen. Steve Daines (R-Mont.).

Democrats said that internal polls over the weekend suggest Comey has not hurt them yet but added that his action was still unwelcome.

“It’s not a good development,” said a Democrat working on Senate races. “Does that affect our races? Maybe.”

Trump pulling closer to Clinton

The presidential campaign plays an undeniable role in Senate races and Trump is steadily gaining on Clinton since his October swoon sent Republicans fleeing from him. Clinton’s lead has dropped from about 7 points two weeks ago to roughly 3 points now, a trend that began before the FBI news.

Clinton still appears to be the overwhelming favorite to win. But Trump looks competitive in Florida and is within striking distance in Nevada, shifts that Republicans hope pay big dividends for them in an uphill battle to keep the Senate.

Still, Republicans fear that the landscape could shift yet again, perhaps with yet another bad story about Trump just before the election.

The Trump effect has been “tremendously damaging,” said Sen. Jeff Flake (R-Ariz.). “With just about any other candidate, we’d have been much better off.”

Shaky Senate polls

Then there's the possibility that we don't know what we think we know about all these competitive Senate races.

Remember Greg Orman? The Kansas independent went into Election Day in 2014 a slight favorite in the polls to win the Kansas Senate race that year. Incumbent GOP Sen. Pat Roberts ended up crushing him by double digits.

That year, pre-election polls favored Democrats by 4 points more than the actual results, according to FiveThirtyEight, which strategists attribute to public polls not reflecting what campaigns were seeing internally. Indeed, Republicans shifted some money from Joni Ernst’s successful run in Iowa that year to other races, even though public polls showed it a toss-up. She won comfortably by 8 points.

This year, public polls largely jibe with internal assessments of competitive Senate races: There are six toss-up races and poll averages show all of them within 4 points. Democrats and Republicans say New Hampshire, North Carolina, Pennsylvania, Missouri, Indiana and Nevada are all toss-ups.

But on the margins, there is disagreement. Florida Democrats say Rep. Patrick Murphy (D-Fla.) is trailing by just a point or 2, not 5 points like in the polls. And Wisconsin Republicans and the Club for Growth insist that Sen. Ron Johnson’s race will be far closer than public polls that sometimes show him down by double-digits. Those surveys have kept Washington GOP money away until a late-game infusion Monday from the Senate Leadership Fund.

“If it’s close and Johnson loses, they’ll look back and say they should have done something more,” McIntosh said.

Ticket-splitting

Republicans are relying on a return to ticket-splitting to save their majority. Voters may pick Democrat Hillary Clinton in the presidential race, but GOP Sens. Pat Toomey of Pennsylvania and Kelly Ayotte of New Hampshire believe they positioned themselves to persuade suburban women to back them for reelection.

But with a week to go, ticket-splitters may actually provide a path for Democrats to seize the majority. While both Ayotte and Toomey are running ahead of Trump, they are doing so by much smaller margins than Democrats Evan Bayh and Jason Kander, who are running ahead of Trump in Indiana and Missouri. Polling averages indicate Bayh, in particular, is running a staggering 11 points ahead of Trump.

And while Republicans have a variety of attacks to deploy against Bayh because of his long record in Washington and the private sector over the past six years, their options are significantly limited when it comes to bringing Kander, an Afghanistan war veteran, down to Clinton’s popularity level. Republicans are worried that the Missouri race has become a referendum on incumbent GOP Sen. Roy Blunt's long history in D.C. and connections to lobbyists.

"Blunt's race is about him," said a Republican working on Senate races. "And he's getting crushed."

Ground game

Senate Republican operatives’ most consistent complaint this cycle has been the Republican National Committee’s failure to build a ground game on the same level as Democrats and Hillary Clinton. While individual campaigns and outside groups — including Americans for Prosperity and Susan B. Anthony List — have tried to make up the gap, some GOP operatives fear Democrats’ get-out-the-vote edge might be worth 3 percentage points or more in the final margin in some states.

Early vote numbers in some states bear this out: Democrats are outperforming their 2008 levels in Florida, and doing better than they did in 2012 in Nevada. But there are some blemishes on the Democratic record: Black turnout in North Carolina is down compared with past years.

Still, GOP operatives are more worried about a drop-off in their own vote than a Democratic surge.

“It’s not that Democrats are so good at this,” one operative said. “It’s that the RNC is so bad.”

Committe spokeswoman Lindsay Walters responded that the RNC "has built a permanent ground game operation that serves as the infrastructure for the entire GOP ticket."

"Both our data operation and field program are being utilized by Senate campaigns in multiple battleground states," she added.