The president is under fire for his repeated attacks on U.S. Attorney General Jeff Sessions and his office for not pursuing criminal charges against his former national security adviser, Michael Flynn.
Sessions resigned in February amid revelations that he lied to the FBI about his contacts with the Russian ambassador to the U.K. and his conversations with Kislyak about sanctions.
He resigned amid allegations that he obstructed justice in a civil case involving the 2016 campaign.
The president’s attacks on Sessions and Trump’s investigation of his former adviser are the latest chapter in a long-running battle with Sessions over Trump’s credibility.
Trump has claimed Sessions was a bad witness and a liar and has threatened to sue Sessions if he doesn’t step aside.
Santorum was first elected in the U, but his Senate seat is now up for grabs.