FILE PHOTO: House Minority Leader Nancy Pelosi (D-CA) speaks during a break in a House Democratic Caucus meeting where she was nominated to be Speaker of the House for the 116th Congress on Capitol Hill in Washington, U.S., November 28, 2018. REUTERS/Joshua Roberts

WASHINGTON (Reuters) - U.S. House Democratic leader Nancy Pelosi said on Thursday that Democrats would try to force protections for U.S. Special Counsel Robert Mueller into a must-pass spending bill if the House is not allowed to vote on a free-standing bill protecting him from potential political interference.

Republicans control the House of Representatives and Senate until January, but they need some Democratic votes on the legislation to keep parts of the U.S. government open beyond Dec. 7.

“The Congress must immediately pass legislation to preserve the Special Counsel investigation,” Pelosi said in a statement.

“If Speaker Ryan refuses to take up that bill, House Democrats will fight to include language to protect the investigation in the upcoming must-pass spending bill,” she added.

Mueller is investigating Russia’s alleged meddling in the 2016 U.S. presidential election and whether the Trump campaign colluded with Moscow.

On Thursday, Trump’s former lawyer Michael Cohen pleaded guilty to lying to Congress, a plea that stemmed from Mueller’s probe.