Two Michigan House Democratic holdouts shifted their stance on backing impeachment proceedings late Monday after allegations that President Donald Trump sought a foreign government's help digging up dirt on a political opponent.

U.S. Reps. Debbie Dingell and Elissa Slotkin for months had opposed an impeachment inquiry, but both said Monday that the new information emerging in recent days regarding Trump's actions had changed their thinking.

Slotkin, a lawmaker from Holly, joined six other House freshman with military or national security experience in advocating impeachment hearings if Trump used taxpayer money in an attempt to coerce Ukraine into investigating political rival former Vice President Joe Biden.

"These allegations are stunning, both in the national security threat they pose and the potential corruption they represent," Slotkin said in a joint essay with her colleagues in the Washington Post.

"If these allegations are true, we believe these actions represent an impeachable offense."

Dingell, D-Dearborn, also backed impeachment proceedings during an interview on MSNBC and in a subsequent tweet.

"After recent revelations, I support an impeachment inquiry because we must follow the facts and hold the President accountable," Dingell wrote.

She had long argued that impeachment would "tear the country apart."

"This country is divided. We cannot be divided on the rule of law," Dingell wrote Monday. "As an elected official my oath is to protect national security and the Constitution."

More than half of Democrats in the U.S. House including four from Michigan have previously backed impeachment: Reps. Dan Kildee of Flint Township, Brenda Lawrence of Southfield, Rashida Tlaib of Detroit and Andy Levin of Bloomfield Township, as well as Sen. Debbie Stabenow, D-Lansing.

Rep. Justin Amash, who left the Republican Party to become independent this summer, has also called for impeachment hearings.

The growing pressure over impeachment comes after the Trump administration has refused to turn over to Congress a whistle-blower complaint reportedly related to Trump's communications with the new Ukrainian president.

Trump had phoned the Ukrainian leader, Volodymyr Zelensky, and urged him to probe unsubstantiated claims that former Vice President Joe Biden and his son Hunter were involved in corrupt business activitiesin the former Soviet Union republic.

At the time of the call, Trump's administration was withholding over $390 million in aid to Ukraine, according to the Washington Post, which reported that Trump had told his chief of staff to freeze the aid package days before the July 25 call.

Trump on Monday continued to insist his actions were appropriate and denied allegations that he was holding back the aid package in an effort to pressure Zelensky to investigate the Bidens.

Trump told reporters there was "no quid pro quo" when he talked to Zelensky on July 25.

Both Dingell and Slotkin had been reluctant to call for impeachment, but congressional Democrats quickly grew frustrated with the Trump administration's blocking of their requests for documents related to the recent allegations.

"Despite federal law requiring the disclosure of this complaint to Congress, the administration has blocked its release to Congress," Slotkin wrote in the Post commentary along with Reps. Gil Cisneros, Jason Crow, Chrissy Houlahan, Elaine Luria, Mikie Sherrill and Abigail Spanberger.

"This flagrant disregard for the law cannot stand. To uphold and defend our Constitution, Congress must determine whether the president was indeed willing to use his power and withhold security assistance funds to persuade a foreign country to assist him in an upcoming election."

Slotkin is a former Central Intelligence Agency agent, and her colleagues, who either served in the military or held national security posts, urged Congress to consider using all powers available, "including the power of 'inherent contempt' and impeachment hearings, to address these new allegations."

House Speaker Nancy Pelosi, D-California, has been holding back party members from pursuing impeachment because it was considered a politically losing proposition based on public polling.

A May 28-30 statewide poll showed most Michigan voters opposed launching impeachment proceedings.

Slotkin a former Defense Department official, represents a Republican-leaning district where she defeated Republican former Rep. Mike Bishop of Rochester by nearly 4 percentage points in 2018.

Dingell represents the predominantly Democratic 12th District, including blue-collar workers in a portion of Wayne County.

Democratic Sen. Gary Peters and freshman Rep. Haley Stevens, D-Rochester Hills, have not backed impeachment.

In June, Stevens told The Detroit News she wanted congressional investigations to be completed and "that we should be in a rush for something as serious as impeachment."

mburke@detroitnews.com