UPDATE 2-U.S. Deputy Attorney General Rosenstein heads to White House amid reports he will resign

U.S. Deputy Attorney General Rod Rosenstein, who oversees the special counsel investigation into Russia's role in the 2016 presidential election, headed to the White House on Monday amid reports he has offered to resign in anticipation of being fired by President Donald Trump, media reports said.

Rosenstein, the No. 2 Justice Department official, verbally resigned to White House Chief of Staff John Kelly, Axios reported, citing an unidentified source with knowledge of the matter.

A second source told Axios that Rosenstein is "expecting to be fired” so he plans to step down.

NBC News reported that Rosenstein said he would not resign and the White House would have to fire him.

Trump faces mounting pressure from the investigation by special counsel Robert Mueller, who is looking into Russia's role in the 2016 presidential election.

Rosenstein assumed supervision of the probe after his boss, Attorney General Jeff Sessions, recused himself because of his own contacts with Russia's ambassador to Washington while serving as a Trump campaign adviser became public.

There was widespread speculation that Trump would fire Rosenstein after a New York Times report on Friday said in 2017 he had suggested secretly recording Trump and recruiting Cabinet members to invoke a constitutional amendment to remove him from the office.

The Times said none of those proposals came to fruition. Rosenstein denied the report as "inaccurate and factually incorrect."

MSNBC and CNN reported Rosenstein was summoned for a meeting at the White House on Monday.

The move comes just six weeks ahead of the Nov. 6 congressional elections and could become an explosive political issue as Trump's fellow Republicans try to keep control of Congress.

Trump has regularly dismissed the investigation as a "witch hunt."