Three-way race in Pennsylvania will again test the Trump factor Tuesday

Former President Trump on Monday night attempted to give Dr. Mehmet Oz, his endorsed candidate in Tuesday's too-close-to-call Pennsylvania GOP Senate primary, a boost to the finish line with a robocall attacking OZ's two closest competitors. 

"These are not candidates who put America first," Trump said of challengers David McCormick and Kathy Barnette.

He called David McCormick, a hedge fund manager, "an insider who absolutely sold us out to China." And he said Barnette once proposed erecting a statue of the Obama family in Washington, D.C. 

"That's no good," Trump said.

Barnette, whose campaign has surged in recent days to make the three-way race a dead heat, is a black military veteran and political commentator who has aligned her politics beliefs with Trump's.

But due to her late-in-the-race surge, there has been little time for rivals to vet her past.

"People don't know her. She hasn't been properly vetted," Trump recently told the Washington Post. "She ran for Congress fairly recently, and she lost by about 20 points." 

Barnette reportedly participated in the January 6 "Stop the Steal" rally in support of overturning the 2020 presidential election.