Democratic leaders and party strategists are zeroing in on Indiana, North Carolina and Missouri, sending major resources to traditional Republican states in the hopes of returning to power after losing the majority in 2014.
"I want them all," Montana Sen. Jon Tester, chairman of the Democratic Senatorial Campaign Committee, told CNN. "I think they are tough states, but they're states we can win in."
The move is a reflection of a rapidly shifting terrain, where GOP senators -- and Donald Trump -- are gaining a surge of support in crucial states, narrowing the Democrats' path to hold the White House and win back the Senate majority. CNN/ORC polls this week showed Republican Sens. Marco Rubio in Florida and Rob Portman in Ohio up by double digits against their respective foes.
On Friday, the Democratic Senatorial Campaign Committee made plans to spend another $4.2 million in North Carolina, on top of an additional $2 million in Missouri, according to a source familiar with the matter. It plans to keep its reservations in Florida for the final three weeks of the campaign and final two weeks in Ohio -- for now.
Sen. Roger Wicker, chairman of the National Republican Senatorial Committee, said "I surely do," when asked if he believed Democrats could win the three red states. "We know that we're in a horserace. We're in a fight. It's going to be very expensive -- hundreds of millions of dollars will be spent in these competitive Senate races."
Republicans view the heightened Democratic focus on red-state battlegrounds as an implicit recognition that the map has significantly narrowed, and that their adversaries now have a tougher climb to the majority. But top Republicans are warning that they could lose those states even though they typically vote GOP, urging their donors -- and their candidates -- to step it up.
Republican groups, including the Senate Leadership Fund super PAC tied to Senate Majority Leader Mitch McConnell and its allied non-profit, plan to drop a combined $16 million in those three states alone, according to an official with the group.
In Missouri, where Democrats are targeting incumbent Sen. Roy Blunt, the party has ramped up its ad reservations substantially, with groups now planning to spend at least $8 million from now until Election Day to help their candidate, Jason Kander, according to media tracking sources.
The DSCC has now reserved nearly $7 million in new ads targeting GOP Sen. Richard Burr in North Carolina, in the hopes of giving a boost to Democrat Deborah Ross, who polls say is trailing by just a few points. Republicans have privately raised concerns that Burr has not run an aggressive campaign against Ross, giving Democrats hopes of pulling off an upset.
And in Indiana, where former Sen. Evan Bayh's campaign has already spent roughly $5 million so far, his campaign and Democratic groups have reserved nearly $6 million for the fall campaign -- in line with the amount of cash the GOP plans to bolster Rep. Todd Young's candidacy. Senate Minority Leader Harry Reid's allied super PAC, Senate Majority PAC, is ramping up spending in Indiana as well.
"I think they're running out of targets," Texas Sen. John Cornyn, the No. 2 Republican in the Senate, said of Democrats. "It's evidence that the election is looking more positive for us and more desperate for them."
Despite the heightened focus on these three states, the battle for control of the Senate still extends into blue and purple states as well. To win back the Senate, Democrats need to pick up four seats if Hillary Clinton wins the White House, five if Trump wins. They are ahead in two Democratic-leaning states, Wisconsin and Illinois, and have a serious shot at winning in New Hampshire and Pennsylvania.
Moreover, Sen. John McCain, R-Arizona, remains a Democratic target, but he has opened up a double-digit lead in recent polls over Rep. Ann Kirkpatrick. Plus, Democrats need to hold onto the seat being vacated by Reid in Nevada, where polls show GOP Rep. Joe Heck in a dead heat with his challenger, Catherine Cortez Masto.
On Friday, Reid dismissed all the polls, predicting his party would retake the Senate majority.
"I don't buy your silliness with your $500 polls you go out and buy overnight," Reid told CNN. "I don't believe them. They're not right. They're incorrect."
Reid added: "Donald Trump will never be elected president of the United States. We're going to retake the Senate."
Tester, the DSCC chairman, said that he has not given up on Florida and Ohio, saying that the Democratic candidates there -- Florida Rep. Patrick Murphy and former Ohio Gov. Ted Strickland -- still can win, despite the polls.
"Those are states the presidential is going to be playing in," Tester said. "We've got good candidates, and I think things are going to tighten up for us in states where we're behind."
But both sides are still influenced heavily by the top of their ticket. And with Clinton's struggles of late, Democrats are having a hard time running significantly ahead of her. Tester said he'd advise candidates to make their own decisions to campaign with Clinton.
"I think it depends on the candidate," Tester said. "It depends on the state, depends on what they feel comfortable with."
Wicker added that Trump now is helping his candidates down-ticket, a sharp shift from weeks ago when the Senate GOP was running away from its nominee.
"I think the top of the ticket helps," Wicker said. "To the extent that voters are motivated to get out and vote in a close race, I think it helps us down-ticket."