WASHINGTON (Reuters) - A leading progressive voice in the U.S. House of Representatives called on Thursday for intensifying the probe into President Donald Trump’s behavior in office with the goal of determining whether to impeach him by year’s end.

FILE PHOTO: Democratic U.S. House committee chairmen Representative Jerrold Nadler (D-NY), Rep. Adam Schiff (D-CA), Rep. Eliot Engel (D-NY), Rep. Elijah Cummings (D-MD), Rep. Maxine Waters (D-CA) and Rep. Jim McGovern (D-MA) hold a news conference to discuss their investigations into the Trump administration on Capitol Hill in Washington, U.S. June 11, 2019. REUTERS/Jonathan Ernst

Democratic Representative Ro Khanna, vice chair of the 98-member Congressional Progressive Caucus, told reporters he thought former Special Counsel Robert Mueller’s multiple findings of obstruction by Trump formed the strongest basis for impeaching the Republican president.

“I think it would be helpful if we were able to get through the process by the end of the year, before the political season really gets on the way,” Khanna said.

He was referring to the presidential nominating contests that start early next year, kicking off with the Iowa caucuses on Feb. 3. Twenty Democrats are vying for their party’s nomination to face Trump in the November 2020 election.

House Speaker Nancy Pelosi and other more moderate Democrats have urged caution in pursuing impeachment amid opinion polls showing only lukewarm support for it.

So far, at least 127 House Democrats, out of 235, have registered their support for impeachment proceedings. At least 218 votes are needed to approve formal charges.

House Judiciary Committee Chairman Jerrold Nadler has held a series of hearings on Trump and has been looking into his 2016 presidential campaign’s contacts with Russian operatives amid multiple findings that Moscow tried to influence the U.S. election that year in Trump’s favor and sow U.S. political divisions.

Trump has denied any wrongdoing and has repeatedly said that investigations into his 2016 campaign and actions since taking office in January 2017 are a “witch hunt.”

Khanna said that if House investigations were to spill into the 2020 presidential and congressional election year, he feared Democrats “would unfairly be accused of being political,” which many Republicans already contend.

“We have to be meticulous, we have to be comprehensive, but I think there’s enough time if we start addressing things in September to get the work done this year,” Khanna said of the need to quicken the pace on an impeachment probe.

Pelosi has called on fellow Democrats to methodically probe Trump, but has said holding House votes on impeaching him could be a waste of time given the lack of support so far among Senate Republicans. Removing Trump from office would require a two-thirds vote by the Republican-controlled Senate.

Democrats hesitant about impeachment have instead urged that efforts be focused on defeating him in his 2020 re-election bid.