 -- Donald Trump supporter Rick Santorum said Sunday that he isn't comfortable with what he called a "cozy relationship" between the White House and presumptive Democratic nominee Hillary Clinton. The former Pennsylvania senator suggested that President Obama may have inside information about the FBI investigation into Clinton's use of a private email account as secretary of state.

"The fact that he’s going to campaign for her, in the face of this looming investigation and potential indictment, shows that maybe he knows something that the rest of us don’t know," Santorum said on ABC's "This Week."

Clinton gave a voluntary interview to the FBI yesterday about her email arrangements during her tenure at the State Department, and Donald Trump was quick to attack her for her email use tweeting that "It is impossible for the FBI not to recommend criminal charges against Hillary Clinton. What she did was wrong!"

Santorum told ABC's Martha Raddatz he believes "a lot of people, not just Donald Trump, are very concerned that this isn’t getting a fair hearing.”

The former 2016 Republican presidential candidate and one-time Trump rival also expressed his concerns over Bill Clinton's meeting last week with Attorney General Loretta Lynch, although he said the meeting should not lead Lynch to recuse herself from the investigation into Hillary Clinton's emails.

"I think the attorney general should be the attorney general. She should go out there and make the case as to why [Hillary Clinton] shouldn't or should be indicted. I don't think recusal is appropriate; she should take the responsibility that comes with the office," he said.

With the Republican National Convention just weeks away and speculation growing as to who Trump will pick to be his running mate, Santorum said the presumptive GOP nominee should look to his former rivals for his VP pick.

"There's lots of good people out there in the Republican Party. There were 17 of us running for president, so that's probably a good place to start," Santorum said, adding that he would not comment on VP speculation about himself.

Santorum said that he feels Trump is qualified to be president, telling Raddatz: "He's a good businessman. He knows how to put the deal together. And I think he'd be a -- he'll be a very constructive figure in the White House."