This week, the legal cloud hanging over President Trump grew darker.

According to The Washington Post, special counsel Robert Mueller is now investigating Trump for possible obstruction of justice.

The growing scandal around Russian election hacking and the firing of the FBI director are prompting many progressives across the country to say it’s time to begin impeachment proceedings against the president now.

John Bonifaz, a constitutional lawyer who heads Free Speech for People, a small progressive group in Amherst, is part of the vanguard of a grassroots movement that has opposed Trump since his first day in office.

"We've launched ImpeachDonaldTrumpNow.org, which now has the support of 1.1 million Americans across the country," Bonifaz says.

Bonifaz says Trump is violating the Foreign Emoluments Clause of the Constitution for failing to fully divest from his private business interests before he took the oath of office. Similar concerns prompted nearly 200 Democratic members of Congress to file suit against the Trump administration this week. The White House dismisses the suit as politically motivated and unfounded, but Bonifaz says there are other reasons to impeach Trump.

"We have since expanded our grounds for this call to include obstruction of justice in light of the president's interference with an ongoing criminal investigation with the firing of FBI Director James Comey," Bonifaz says.

According to The Washington Post, special counsel Robert Mueller is now investigating President Trump for possible obstruction of justice. (Evan Vucci/AP)

Along with the million-plus people who've signed Bonifaz's petition, about a dozen U.S. cities and towns have passed resolutions calling for impeachment, including Los Angeles and Chicago, as well as Amherst, Cambridge, Pelham and Leverett here in Massachusetts.

And after Comey's congressional testimony last week, two national grassroots organizations, Indivisible and MoveOn.org, which oppose Trump, also urged Congress to start impeachment proceedings.

"More people support impeaching Trump than approve of his job performance," says Anna Galland, MoveOn's executive director. According to a recent Politico/Morning Consult poll, she's right — though the poll also found the country deeply divided over this issue, with a slim plurality opposing impeachment.

Still, Galland says it's time to act now.

"There have been sufficient evidence of what are called in the Constitution ‘high crimes and misdemeanors,’ and we think it's time for all members of Congress — both Democrats and Republicans — to support moving forward with impeachment proceedings,” Galland says.

But that's not happening. For the most part, Republicans in Congress remain in lockstep behind the president and don't support impeachment. And so far, just two Democrats — U.S. Reps. Brad Sherman of California and Al Green of Texas — say they do.

"We live in a country where no congressman, no senator and not even the president of the United States is above the law," Green said earlier this week. "And I've concluded that as a result articles of impeachment should be drawn."