The Senate map is expanding for Democrats under Donald Trump Donald John TrumpBiden leads Trump by 36 points nationally among Latinos: poll Trump dismisses climate change role in fires, says Newsom needs to manage forest better Jimmy Kimmel hits Trump for rallies while hosting Emmy Awards MORE, whose weakness in key battlegrounds has created new vulnerabilities for Republicans.

The good news for the GOP is that Sen. Rob Portman Robert (Rob) Jones PortmanMcConnell locks down key GOP votes in Supreme Court fight Romney undecided on authorizing subpoenas for GOP Obama-era probes Congress needs to prioritize government digital service delivery MORE has solidified his position in Ohio, a hotly contested battleground, and Sen. Marco Rubio Marco Antonio RubioSunday shows preview: Justice Ginsburg dies, sparking partisan battle over vacancy before election Florida senators pushing to keep Daylight Savings Time during pandemic Hillicon Valley: DOJ indicts Chinese, Malaysian hackers accused of targeting over 100 organizations | GOP senators raise concerns over Oracle-TikTok deal | QAnon awareness jumps in new poll MORE’s high name identification gives the party a much better chance of holding Florida’s Senate seat.

ADVERTISEMENT

The Republican presidential nominee's recent plunge in the polls in North Carolina, however, has vaulted Sen. Richard Burr Richard Mauze BurrRep. Mark Walker says he's been contacted about Liberty University vacancy Overnight Defense: Trump rejects major cut to military health care | Senate report says Trump campaign's Russia contacts posed 'grave' threat Senate report describes closer ties between 2016 Trump campaign, Russia MORE into the ranks of the Senate’s most vulnerable incumbents, according to Democratic and Republican strategists.

Republicans are also getting nervous about Missouri, where incumbent Sen. Roy Blunt Roy Dean BluntMcConnell locks down key GOP votes in Supreme Court fight Murkowski: Supreme Court nominee should not be taken up before election Battle lines drawn on precedent in Supreme Court fight MORE faces a difficult challenge from Democratic Secretary of State Jason Kander, a former Army captain.

The Senate Leadership Fund, a group close to the Senate GOP leadership, and One Nation have allocated $2.1 million and $993,000 since Aug. 1, respectively, to defend Blunt, according to a source who tracks media buys.

Indiana is another state where the possibility of a Democratic pickup is looking much more likely now that former Sen. Evan Bayh (D) has jumped into the race. Bayh is helped enormously by his near universal name identification in the state and his more than $9 million in cash on hand.

Democratic strategists now rank Indiana as a more likely pickup than New Hampshire, Ohio and Pennsylvania, where GOP Sens. Kelly Ayotte Kelly Ann AyotteBottom line Bottom line Bottom Line MORE, Portman and Pat Toomey are fighting, respectively, to save their seats.

Democrats need to gain five seats — or four seats and retain control of the White House — to win back the Senate majority.

Sens. Mark Kirk Mark Steven KirkLiberal veterans group urges Biden to name Duckworth VP On the Trail: Senate GOP hopefuls tie themselves to Trump Biden campaign releases video to explain 'what really happened in Ukraine' MORE (R-Ill.) and Ron Johnson Ronald (Ron) Harold JohnsonGOP set to release controversial Biden report Democrats fear Russia interference could spoil bid to retake Senate The Hill's Morning Report - Sponsored by The Air Line Pilots Association - White House moves closer to Pelosi on virus relief bill MORE (R-Wis.) are big underdogs in their races. Democratic nominee Hillary Clinton Hillary Diane Rodham ClintonBiden leads Trump by 36 points nationally among Latinos: poll Democratic super PAC to hit Trump in battleground states over coronavirus deaths Battle lines drawn on precedent in Supreme Court fight MORE is far ahead of Trump in Illinois and Wisconsin, and some believe those two GOP seats may already have been lost.

Democrats also do not appear to be in trouble of losing any seats.

The GOP’s best shot for a pickup may be Nevada, where GOP-allied outside groups have significantly outspent their Democratic counterparts to promote Rep. Joe Heck. Even so, they have to defeat the political machine that retiring Senate Democratic Leader Harry Reid Harry Mason ReidDemocrats fear Russia interference could spoil bid to retake Senate Graham signals support for confirming a Supreme Court nominee this year Trump signals he will move to replace Ginsburg 'without delay' MORE built up over decades. He has made keeping his seat Democratic a top personal priority.

Republicans entered the 2016 cycle knowing they were in for a difficult fight. They are defending 24 seats compared to just 10 for Democrats.

The fight appears to have grown more difficult with Trump at the top of the ticket.

In New Hampshire and Pennsylvania, Trump is behind Clinton in some polls by double-digits, meaning Ayotte and Toomey must fight against the current.

A WBUR poll published Aug. 4 showed Clinton crushing Trump by 17 points in a head-to-head contest in New Hampshire and by 15 points when third-party candidates were included.

An NBC/Wall Street Journal poll released Aug. 10 showed Clinton leading Trump by 11 points in Pennsylvania in a head-to-head matchup and 9 points in a four-way race.

“We’ve got a fantastic group of senators who are fighting against serious headwinds, all of whom have built campaigns to stand a drag atop the ticket,” said one Senate Republican strategist. “But there’s a limit beyond which even the best candidates can’t survive.”

Republicans point to a recent NBC/Wall Street Journal poll showing Clinton with a 9-point lead in North Carolina to argue that Trump is becoming a major drag on Burr.

The same poll shows Burr’s opponent, former state Rep. Deborah Ross, who was little known before the race, with a 2-point lead.

One of the big problems for Burr is that Clinton and her allies are targeting the state heavily, while Trump has let their attacks go largely unanswered.

Priorities USA, a super-PAC backing Clinton, announced a $9 million ad buy in North Carolina in June.

Earlier this month, the group teamed up with VoteVets PAC, another pro-Democratic committee, to run a statewide ad in North Carolina and other states hitting Trump over his war of words with Khizr Khan, a Muslim who spoke about his son’s combat death during the Iraq War at the Democratic National Convention.

One Republican strategist said North Carolina is now more competitive than Ohio or Florida.

“Trump is not doing great in North Carolina. He’s not down 10 to 15 points,” said the strategist, who called Trump’s drag in North Carolina significant.

Another strategist said Trump is a problem for Blunt in Missouri.

“I might put Missouri in front of Ohio,” said the second strategist.

A Senate Democratic strategist said Democrats are seeing more opportunities.

“I don't think the map is changing as much as it's expanding,” the source said.

While Republicans are putting more money into North Carolina and Missouri, they're not easing up on New Hampshire, Florida, Ohio and Pennsylvania, which have been long identified as the key defensive positions to protect the Senate GOP majority.

Through the doom and gloom, Portman and Rubio are standing out as bright spots for Republicans, even though they still have tough races.

An average of public polls compiled by RealClearPolitics shows Portman with a 5.8-point lead over his Democratic challenger, former Gov. Ted Strickland.

Portman has also put together a record-breaking get-out-the-vote operation, which he showcased to the media during the Republican National Convention in Cleveland. His campaign had made nearly 3 million voter contacts by the end of July.

Democrats argue that pro-GOP outside groups have already spent more than $32 million against Strickland, who unveiled his first television ad buy just last week. His campaign has reserved $8 million worth of airtime for the 60-second spot after Labor Day.

Democrats say Clinton will also run a huge get-out-the-vote operation in Ohio that Trump and the Republican National Committee won’t come close to matching. Republican operatives on the ground admitted during the GOP convention that the Trump/RNC joint voter mobilization effort in Ohio was underwhelming.

A Monmouth poll released Tuesday shows Rubio leading Democratic Rep. Patrick Murphy (Fla.), his most likely challenger, by five points. That’s a remarkable feat considering the same survey shows Clinton with a 9-point lead over Trump.

Republican strategists are bullish over Rubio’s chances, especially after a few gaffes by Murphy, who misstated his experience as a certified public accountant and somewhat oddly described himself as an immigrant, which conservative groups pounced on. Murphy also still has to beat Rep. Alan Grayson Alan Mark GraysonFlorida's Darren Soto fends off Dem challenge from Alan Grayson Live results: Arizona and Florida hold primaries The Hill's Morning Report: Frustration mounts as Republicans blow up tax message MORE in the Aug. 30 primary.

Murphy is little known outside his congressional district, something that will cost tens of millions of dollars in television spending to remedy.

But the Democratic Senatorial Campaign Committee (DSCC) and allied outside groups such as Senate Majority PAC still think Ohio and Florida are ripe targets and have planned huge ad buys in those states.

“Rubio is still very vulnerable. Portman isn't safe but has put himself in a position to survive except in a Trump collapse,” said Larry Sabato, director of the University of Virginia’s Center for Politics.

Senate Majority PAC has $10.5 million in television airtime reserved in Florida starting after Primary Day. The DSCC has $10.6 million in airtime reserved, according to a Democratic operative who tracks buys.

Freedom Partners, a GOP-allied group, plans a $3.3 million television buy in Florida to boost Rubio after the primary.

Both sides have big buys planned for Ohio, which despite Portman’s relatively comfortable position, is still hotly contested.

Since Aug. 1, the Senate Leadership Fund has allocated $7.9 million; the National Republican Senatorial Committee has called for $6.9 million; the U.S. Chamber of Congress has spent or reserved $1.1 million; Fighting for Ohio has added $1.5 million; and Freedom Partners has allocated $4.8 million on the Republican side, according to a GOP source who tracks buys.

On the Democratic side, Senate Majority PAC, the DSCC and the American Federation of State, County and Municipal Employees have spent or reserved a total of $22.6 million in Ohio, according to the same source.