Politico reports that one of that one of those candidates is Lynda Blanchard, who is running for the Alabama Senate.
Ms Blanchard donated $1m to a pro-Donald Trump political committees and served as his ambassador to Slovenia.
When she launched her campaign, Ms Blanchard used a video pumping her Trump bonafides, including a pickup truck decorated with a Trump bumper sticker.
Mr Trump is believed to be backing Rep Mo Brooks, a primary challenger to Ms Blanchard who championed the former president's fraudulent challenge to the 2020 election and who spoke at the rally that preceded the Capitol riot.
The former president reportedly complained to his advisers that he barely knew Ms Blanchard.
In response, Ms Blanchard's staff said the campaign ad was never meant to suggest she had Mr Trump's support, but that she supported him.
Numerous Republicans have made their support of Mr Trump a centre-point of their campaigns, all vying to appeal to the conservative base that still largely favours the former president.
Mr Trump's former campaign manager, Corey Lewandowski, said most of them are lying.
“Lots of candidates pretend to have the support of President Trump. Most are full of s***. You will know when President Trump endorses someone,” he said.
While Mr Trump frequently touts his popularity among Republican voters, he is also deeply protective of his political brand and appears to view his endorsements as essentially an anointment.
In one instance Mr Trump invited four Ohio Republicans to Florida to compete for his endorsement in an upcoming senate race to fill Senator Rob Portman's seat.
In a 15-minute meeting at Mar-a-Lago, he set the candidates against each other, forcing them to make the case for who should receive his coveted endorsement.
It is clear Mr Trump wants his endorsement to be a gold standard for candidates, and his staff have fought people who have fraudulently suggested they are his chosen pick.
Last year his campaign staff sent cease-and-desist letters to his former US Attorney General Jeff Sessions, who was running for the Alabama Senate as well as candidates running for local offices.
More recently, a flier began circulating on the internet that Mr Trump had endorsed Hirsh Singh, a conservative businessman running for governor of New Jersey.
The flier was reportedly made to mimic Mr Trump's occasional missives to lend it credibility. Mr Trump's spokesman, Jason Miller, issued a tweet saying the fliers were "FAKE" and confirming that the former president "has NOT endorsed in the race."
Mr Singh denied any involvement with the flier, claiming one of his opponents was behind the scheme in an attempt to embarrass him, saying "I don't play sneaky games like this."
Prior to that, Mr Miller also objected to claims made by Doug Mastriano, who is running for the Pennsylvania state senate, that Mr Trump had asked him to run, saying "Doug, run and I'll campaign for you."
Mr Trump's spokesman again said that the former president "has not made any endorsement or commitments yet."
Another instance occurred in April, when Mr Trump's team rejected claims made by Dan Rodimer, a former professional wrestler-turned-political candidate running for the Texas House of Representatives.
Mr Rodimer ran ads claiming he was the "Trump candidate" and that he was the only candidate in the race that "has ever been endorsed by President Trump."
Mr Miller again knocked down the claims, saying that "President Trump has NOT yet endorsed a candidate."
Mr Rodimer claimed he "did not imply we had Trump's support" with the ad.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies