BOSTON — Sen. Elizabeth Warren is making the case for impeaching Republican President Donald Trump, even as she seeks the Democratic nomination to challenge his re-election next year.

Warren, the first of a crowded field of Democratic presidential candidates to call for Trump’s impeachment, doubled down on her position on Wednesday following an ABC News interview in which Trump said he would listen to an offer for information about a political opponent from a foreign government.

"The #MuellerReport made it clear: A foreign government attacked our 2016 elections to support Trump, Trump welcomed that help, and Trump obstructed the investigation. Now, he said he'd do it all over again. It's time to impeach Donald Trump," Warren tweeted.

Still, Warren's stance on impeachment puts her somewhat at odds with the state's other senator, Democrat Ed Markey, and other lawmakers in the 11-member, all-Democratic congressional delegation. Many take a more cautious approach to the question of whether Congress should begin proceedings to remove Trump from office.

Reps. Stephen Lynch, Lori Trahan, Joe Kennedy, Katherine Clark and Richard Neal, while all critical of the president's leadership, stop short of calling for impeachment.

They've aligned themselves with House Speaker Nancy Pelosi, who is focused on congressional oversight hearings as a way to hold Trump accountable for his actions in office.

"President Trump's failure to acknowledge the oversight role of Congress is a direct threat to our system of government, and risks harming the people I ran for office to represent," Trahan, a Westford Democrat, said in a statement. "My colleagues in Congress are working to uncover the truth, and they must be allowed to continue their important work."

"Impeachment is always on the table, and if the president continues to hold himself above the law, Congress will be prepared to take that step," she added.

To be sure, Warren isn't isolated in her view on impeachment: Reps. Seth Moulton and Ayanna Pressley support it.

Moulton, who is also running for president, makes the case that Congress can no longer ignore the president's efforts to obstruct investigations into potential wrongdoings.

"It is Congress’ duty to respond to the charges addressed by the Mueller report by beginning impeachment proceedings immediately, so we can have this debate transparently before the American people," the Salem Democrat said recently. "That is our Constitutional responsibility, regardless of the politics."

Pressure has increased on Democrats following comments last month by special counsel Robert Mueller in which he noted multiple White House efforts to obstruct investigations into Russian meddling in the 2016 presidential elections.

Mueller said charging Trump with a crime was "not an option" because of federal rules, but he emphasized that his report did not exonerate the president.

House Judiciary Chairman Jerry Nadler, a New York Democrat whose committee would lead impeachment proceedings, has initiated several probes into obstruction of justice by Trump and members of his administration following release of Mueller's report. Nadler has said "all options are on the table."

The U.S. Constitution allows Congress to remove presidents before their terms are finished if enough lawmakers vote to say that they committed "treason, bribery, or other high crimes and misdemeanors.” Removal requires a simple majority vote in the House and a trial in the Senate, where two-thirds of the upper chamber would have to vote to convict.

So far, none of the state's congressional lawmakers have said they oppose impeachment.

Political observers say Warren and Moulton's prospective bids for the White House in 2020 are likely a major factor in their hard-line positions on impeaching Trump.

"They clearly have an eye towards winning the nomination," said Erin O'Brien, chairwoman of the political science department at the University of Massachusetts at Boston. "So it's really not surprising to see them out front on the issue when they're in a highly competitive Democratic primary where party activists are very much for impeachment."

O'Brien said the divide over how to deal with Trump exposes ideological differences between members of the state's congressional delegation.

"Impeachment is one of those litmus tests where you can see who's more progressive and who's on the centrist, business side of the party," she said.

Observers say the risk for Democrats is if they open proceedings but fail to remove him, Trump could claim they overreached and that Congress had exonerated him.

Phil Johnston, a longtime political consultant and former chairman of the state's Democratic Party, said Pelosi's sway is likely another factor in the divide over impeachment.

"Speaker Pelosi has great influence over her members," he said. "As long as she feels that going down that road is risky, many Democrats will hold off supporting impeachment."

Christian M. Wade covers the Massachusetts Statehouse for The Salem News and its sister newspapers and websites. Email him at cwade@cnhi.com.