An endorsement by former President Donald Trump in Pennsylvania's hotly contested U.S. Senate race isn't backing down rival Republicans, with one putting up millions for her campaign and another getting a seven-figure pledge from a donor.

Carla Sands, Trump's ambassador to Denmark, loaned her campaign $3 million, according to her first federal fundraising report.

Sands, 61, has significant personal wealth left over from her and her late husband's California-based real estate investment firm, and her campaign said Oct. 15 that the first-time candidate is willing to put more of her personal money into the race.

Another candidate, real estate investor Jeff Bartos, could see significant help from a super PAC supporting him.

Scott Wagner, the GOP's gubernatorial nominee in 2018 and a major Republican campaign donor in Pennsylvania, said Oct. 15 that he has pledged $1.5 million to the Bartos-aligned Jobs For Our Future PAC. He could give more in the future to help Bartos, too, Wagner said.

Trump last month endorsed Sean Parnell, a decorated former Army Ranger who penned a memoir of his service in Afghanistan, which became a New York Times bestseller.

But Wagner said he doesn't know how much weight Trump's endorsement holds.

"I don't necessarily think it's a slam dunk because of an endorsement," Wagner said. "Right now, the political winds are shifting pretty quickly."

And while Wagner said the Republican Party is not necessarily moving away from Trump, he also said the election will not be about who Trump endorses.

"I think they're going to vote for the best candidate," Wagner said. "That's what this is all about."

The contest for Pennsylvania's open U.S. Senate seat could be among the nation's most competitive next year. For Democrats, it is one of their best chances to gain ground in the Senate since second-term Republican Sen. Pat Toomey is retiring.

For Republican candidates, a Trump endorsement was seen as a crucial element for success in the GOP primary.

It has not, thus far, brought Parnell a fundraising windfall: on Oct. 15 he reported raising $1.1 million in the three months ending Sept. 30. After spending most of it, he had about the same amount left in his campaign account.

Even though Parnell trailed Sands and Bartos in overall cash in their accounts as of Sept. 30, he outraised all of his opponents, combined, when counting dollars from donors during the three months, his campaign pointed out.

He netted four times the amount as Bartos—who has loaned his campaign $1.2 million—and more than twice the amount as Sands.

Still, Trump's endorsement has not always carried the day in primaries for open seats.

Last year, for instance, the Trump-endorsed Lynda Bennett got beaten by Madison Cawthorn for a North Carolina congressional seat. In July, Republican Jake Ellzey of Texas won a U.S. House seat, beating the Trump-backed Susan Wright.

The Democratic field is also crowded. John Fetterman, Pennsylvania's lieutenant governor, reported nearly $4.2 million cash in his campaign account as of Sept. 30 to lead the Democratic field's fundraising.

It's also not clear what value Trump's endorsement has in a general election against a Democrat.

Trump lost Pennsylvania last year by about 80,000 votes, or 1 percentage point, to Joe Biden, who reclaimed the swing state for Democrats after it became a surprising stepping stone for Trump's ascendance to the White House in 2016.

Sands' and Wagner's millions don't necessarily have to be spent.

However, Jobs For Our Future PAC—taking a cue from Bartos' campaign—has already attacked Parnell on TV and online over allegations in his contentious divorce and custody case unfolding in Butler County court.

Meanwhile, Sands—far from moving away from Trump or saving her money—is running a 30-second TV spot on Fox News that opens with a photo of Trump greeting her in the Oval Office.

"Serving on President Trump's economic and foreign policy teams, I helped counter the threats presented by communist China and Putin's Russia," she narrates, before going on to attack Biden over three favorite Trump themes: immigration, socialism and police.