A POLITICO/Morning Consult flash poll in the immediate aftermath of the vote found that voters backed removal 52 percent to 43 percent. But a later poll, conducted earlier this month after House Speaker Nancy Pelosi delayed sending the articles of impeachment to the Senate, found that support for removal had dropped 3 points, to 49 percent, with the percentage of voters opposed to removal remaining the same.

Voter sentiment registered in the latest poll has remained consistent in that it breaks sharply along party lines. Independents split evenly on the question of removal, which would require votes from two-thirds of the Republican-controlled Senate.

The month since the president’s impeachment has resulted in some partisan shifts: While opposition to removal among Democrats remained the same, support for removal among Democrats dropped 2 points, to 84 percent. But Republicans have coalesced in their opposition to removal.

The Senate impeachment trial into President Donald Trump began on Tuesday. | Senate Television via AP

“Republican opposition to impeachment is on the rise as the Senate trial begins,” said Tyler Sinclair, Morning Consult’s vice president. “This week, nearly nine in 10 Republicans (88 percent) disapprove of the Senate removing President Trump from office, compared with only 10 percent who approve. This compares with 80 percent disapproval and 17 percent approval following the House vote last month.”

The POLITICO/Morning Consult poll found more agreement on whether the Senate should allow witnesses to testify in the trial, the subject of sharp disagreement between Republicans and Democrats and the cause for Pelosi’s delay in transmitting the articles.

Nearly 6 in 10 voters, 57 percent, said the Senate should call additional witnesses to testify, including 37 percent of Republicans and 53 percent of independents.

The chamber on Tuesday debated a rules package that does not commit to calling witnesses but leaves the issue up to a majority vote after House managers and Trump’s legal team conclude their opening arguments.