U.S. President Barack Obama warned on Friday that occupying the Oval Office “is not a reality show,” in a swipe at outspoken Republican candidate Donald Trump who is vying to replace him in the White House.

Fighting with Obama is a battle Trump would likely relish as he tries to rally support within his own party. During hard-fought Republican primary campaigns, the billionaire delighted in responding to attacks from rivals and found that his support grew when he lashed out at his opponents.

Asked about Trump at a media briefing in the White House, Obama called on the press and public to weigh past statements by the Republican but did not point to any specific issues or remarks.

“This is not entertainment,” Obama said, a reference to Trump’s television background. “This is not a reality show. This is a contest for the presidency of the United States,” he said.

Early general election polls show Clinton with a lead both nationally and in key states.

Clinton has a higher probability than Trump of becoming the next president, but the gap between them narrowed this week, according to the online political stock market PredictIt.

A key factor for Trump in the general election will be whether he can rally the party behind him.

Trump has seen some top Republicans who previously fought his candidacy now back him, including Texas Governor Rick Perry. Former Vice President Dick Cheney, whose daughter Liz Cheney is running for Congress in Wyoming, said he will support Trump, a source close to him said on Friday.