Sen. Lindsey Graham, R-S.C., defended Attorney General Jeff Sessions after President Trump published a series of tweets criticizing the former Alabama senator and said it was "highly inappropriate" for Trump to suggest Sessions investigate Hillary Clinton.

"Jeff Sessions is one of the most decent people I've ever met in my political life. Jeff Sessions is a rock-solid conservative, but above else he believes in the Rule of Law. He understands we are a nation of laws, not men," Graham said in a series of tweets Tuesday morning.

"On occasion, I've vigorously disagreed with Jeff but I've never once doubted his integrity or sense of fair play."

Early Tuesday morning, the president published several tweets pressuring Sessions to investigate Clinton, his Democratic challenger in the 2016 election, and slamming him for taking a "VERY weak position" on leaks from the intelligence community.

"Ukrainian efforts to sabotage Trump campaign – ‘quietly working to boost Clinton.' So where is the investigation A.G. @seanhannity," Trump said in one tweet, mentioning Fox News host Sean Hannity.

"Attorney General Jeff Sessions has taken a VERY weak position on Hillary Clinton crimes (where are E-mails & DNC server) & Intel leakers!" he said in a second one.

Graham called Trump's tweets "highly inappropriate" and said any prosecutorial decisions should be based solely on facts instead of politics.

"President Trump's tweet today suggesting Attorney General Jeff Sessions pursue prosecution of a former political rival is highly inappropriate," the South Carolina senator said. "Prosecutorial decisions should be based on applying facts to the law without hint of political motivation. To do otherwise is to run away from the long-standing American tradition of separating the law from politics regardless of party."

Over the last two weeks, Trump has set his aim on Sessions and his decision to recuse himself from the investigation into Russian meddling in the 2016 election.

In an interview with the New York Times last week, Trump said he wouldn't have tapped Sessions for attorney general had he known the former senator was going to recuse himself from the Russia probe.

He also criticized Sessions on Twitter on Monday morning, calling his attorney general "beleaguered."

White House aides have also suggested Sessions' days as attorney general may be numbered.

In an interview with radio host Hugh Hewitt on Tuesday morning, White House communications director Anthony Scaramucci suggested Trump wants Sessions out.

"It's clear the president wants him gone, right?" Hewitt asked Scaramucci.

"I have an enormous amount of respect for the attorney general, but I do know the president pretty well, and if there's this level of tension in the relationship that, that's public, you're probably right," Scaaramucci replied.