Senators sharing the ballot with likely Republican nominee Donald Trump are warming up to the idea of supporting the billionaire, but are still hesitant to formally endorse him.
A spokeswoman for Sen. Kelly Ayotte, R-N.H., who's facing a tough challenge in November, reiterated that Ayotte is still planning to support the nominee.
Sens. John Hoeven, R-N.D., Tim Scott, R-S.C., and James Lankford, R-O.K., have also pledged their support, but clarified that their backing shouldn't be confused for an endorsement.
What is uniting these senators behind Trump is their mutual goal to take down Hillary Clinton. A spokesperson for Sen. Lankford said that he's in it to defeat Clinton, but will be focusing his efforts mostly "on keeping the Senate majority, though."
Yet their added support means that more than half of the 21 Republican senators up for re-election this year would unquestionably support Donald Trump if he becomes the party's nominee, according to an ongoing survey by NBC News.
Only eight of these senators--including those facing both safe and competitive contests--enthusiastically responded that they'd back Trump before he became the clear frontrunner.
"I'll support the nominee. I think any of our candidates would be a better president than Secretary Clinton or Senator Sanders," Sen. Roy Blunt, R-Mo, said.
One of the Senate's most vulnerable candidates, Sen. Mark Kirk from Illinois, recently told NBC's Chicago affiliate that if Trump were to clinch the nomination he "certainly would" support him.
Another three GOP senators up for re-election have hedged on whether they'd stand behind Trump if he's the nominee, opting instead to observe the rest of the Republican primary season.
Despite some hesitancy by a few senators, none of the 21 senators facing re-election said they would actively oppose Trump if he becomes the party's nominee.
As for the remaining six senators, they and their offices refused to answer the question, despite multiple attempts by NBC News.
This survey was conducted by contacting these senators' offices and campaigns at least three times in the past several months, as well as by monitoring their past statements. Here are the results:
Senators Backing Trump (12)
Kelly Ayotte (NH)
A spokesperson tells NBC News, "as she's said from the beginning, Kelly plans to support the nominee."
John Boozman (AR)
Campaign spokesperson Chris Caldwell pointed NBC News to an AP interview on March 1:
"U.S. Sen. John Boozman says he'll support Donald Trump in the November election if the billionaire and reality television star is the Republican presidential nominee."
Roy Blunt (MO)
"I'll support the nominee. I think any of our candidates would be a better president than Secretary Clinton or Senator Sanders."
Chuck Grassley (IA)
"I'm going to do everything I can to beat Hillary."
John Hoeven (ND)
"Senator Hoeven is not endorsing in the presidential race. He will support the nominee of the party," campaign spokesperson Don Larson told NBC News.
Johnny Isakson (GA)
"I support the ticket and I'm not endorsing anybody, and I'm not going to talk about it any further than that. I haven't endorsed anybody, and won't, and I'll support the ticket in November."
Mark Kirk (IL)
"The GOP nomination is a long and fluid process right now and we are not going to try to decrypt a very hazy and cloudy crystal ball," Kevin Artly, Kirk's spokesperson, said.
NBC5 Chicago's Mary Ann Ahern asked Kirk on camera if he would support Trump if he becomes the nominee. Kirk, who has not officially endorsed a candidate said, "If he's the nominee I certainly would."
James Lankford (OK)
"In a choice between the Republican nominee and Hillary Clinton, Senator Lankford will work to defeat Mrs. Clinton in November. He will be very focused on keeping the Senate majority, though," a spokesperson for the senator said. The spokesperson clarified that Lankford's support does not count as an endorsement.
John McCain (AZ)
Spokeswoman Rachael Dean told NBC News that the senator has "been very clear on this so I will let his previous statements stand."
When asked by NPR if he would support Trump, McCain repeatedly said "I said I'd support the nominee."
Rand Paul (KY)
"Senator Rand Paul will support the nominee," campaign spokesman Sergio Gor told NBC News.
Tim Scott (SC):
"Senator Scott has consistently stated he will support the Republican nominee, and after last night that appears to be Donald Trump. We can't afford 4 more years of Obama-Clinton, period," campaign spokesperson Margaret Spaulding told NBC News.
Richard Shelby (AL)
"I haven't endorsed anybody, but I will support whoever is the nominee."
Senators Unclear About Trump As Nominee (3)
Richard Burr (NC)
"I've always said I was going to support the nominee, I'm hopeful I'll be able to support the nominee."
Ron Johnson (WI)
"Ron plans to support the Republican nominee for president. He has repeatedly said that he is praying for a nominee of integrity, intelligence, ideas, and courage who can lead our nation - not divide it," Brian Reisinger, Johnson's campaign spokesperson, said.
John Thune (SD)
"Well, I intend to support the nominee. I've made that clear from the very beginning. And we don't know who that's going to be at this point."
No Response (6)
Mike Crapo (ID)
Mike Lee (UT): Sen. Lee was the first senator to endorse colleague Ted Cruz.
Jerry Moran (KS)
Lisa Murkowski (AK)
Rob Portman (OH): Sen. Portman is currently backing Ohio Gov. John Kasich.
Pat Toomey (PA): Sen. Toomey also backed Rubio before he suspended his campaign.