A majority of Americans say they endorse the decision by House Democrats to begin an impeachment inquiry of President Donald Trump, and nearly half of all adults also say the House should take the additional step and recommend that the president be removed from office, according to a Washington Post-Schar School poll.

The findings indicate that public opinion has shifted quickly against the president and in favor of impeachment proceedings in recent weeks as information has been released about Trump’s efforts to pressure Ukrainian government officials to undertake an investigation into former vice president Joe Biden, a potential 2020 campaign rival, and Biden’s son Hunter.

Previous Post-Schar School or Post-ABC News polls taken at different points throughout this year found majorities of Americans opposing the start of an impeachment proceeding, with 37 percent to 41 percent saying they favored such a step. The recent revelations appear to have prompted many Americans to rethink their position.

The poll finds that, by a margin of 58 percent to 38 percent, Americans say the House was correct to undertake the inquiry. Among all adults, 49 percent say the House should take the more significant step to impeach the president and call for his removal from office. Another 6 percent say they back the start of the inquiry but do not favor removing Trump from office, with the remainder undecided about the president’s ultimate fate. The results among registered voters are almost identical.

The findings highlight the partisan divisions that surround the Trump presidency and any impeachment inquiry, but also the degree to which there are defections among Republicans.

More than 8 in 10 Democrats endorse the inquiry and nearly 8 in 10 favor a vote to recommend that Trump be removed from office. Among Republicans, roughly 7 in 10 do not support the inquiry but almost 3 in 10 do, and almost one-fifth of Republicans say they favor a vote recommending his removal. Among the critical voting bloc of independents, support for the impeachment inquiry hits 57 percent, with 49 percent saying the House should vote to remove Trump from office.

Since a July poll by The Post and ABC, there has been movement toward an impeachment inquiry among all three groups, with support for the inquiry rising by 25 points among Democrats, 21 points among Republicans and 20 points among independents.

The impeachment inquiry is moving forward at a steady pace, with House committees issuing more subpoenas on Monday and with additional testimony from witnesses likely later this week. The president, meanwhile, has denounced the Democrats for undertaking the inquiry, and his reelection campaign has begun airing television ads echoing charges, largely unfounded, that the president has made in tweets and statements.

Two pieces of information triggered the impeachment inquiry and have sparked widespread public concern, according to latest survey conducted by The Post and the Schar School of Policy and Government at George Mason University. The first was the rough transcript of a July 25 telephone call between Trump and newly elected Ukrainian President Volodymyr Zelensky, during which Trump asked for “a favor” that included requests for the Ukrainians to look into what happened during the 2016 election and to investigate Biden and his son, who sat on the board of a Ukrainian energy company.

Asked about the contents of the telephone call, a clear majority of Americans say Trump’s request to investigate Biden and his son was inappropriate (62 percent to 32 percent who felt it was not). Over 8 in 10 Democrats call the request inappropriate, as do 63 percent of independents. Republicans have a different view, with nearly 6 in 10 calling the request for the investigation appropriate and one-third saying it was inappropriate.

The president has defended himself, saying he did nothing inappropriate, calling the conversation “perfect” and insisting that he was within his rights to demand investigations into alleged corruption of an ally to which the United States sends significant aid.

In the weeks before the July 25 phone call, the White House had held back military aid that had been approved for Ukraine. Asked how much this matters in judging the president’s actions, 58 percent say it matters either “a great deal” or “a good amount,” while 37 percent say it matters “not so much” or “not at all.”

When it comes to Trump’s overall conduct as president, Americans offer a harsh verdict. Asked whether the president upholds adequate standards for ethics in government, 60 percent of Americans say he does not, while 35 percent say he does.

Partisan divisions mark the results on this question as well, with 83 percent of Democrats and 64 percent of independents saying he does not uphold adequate ethical standards and 68 percent of Republicans saying he does.

The verdict on the former vice president is more positive, if still mixed: Asked whether Biden would uphold adequate standards for ethics in government were he to become president, 47 percent say yes, while 38 percent say no. Those results also split along partisan lines, with 72 percent of Democrats saying Biden would uphold ethical standards, while 63 percent of Republicans say he would not.

The poll finds 15 percent of all Americans say Trump does not uphold adequate ethical standards and say that Biden also would not do so if he were president.

At this early stage in the impeachment inquiry, whose timing is fraught as the country barrels toward an election year, the public is siding more with congressional Democrats than Republicans when it comes to their responses so far. By a margin of 49 percent to 44 percent, Americans narrowly approve of the way congressional Democrats are responding to the inquiry. But by a margin of 56 percent to 33 percent, they say they disapprove of the way congressional Republicans are responding. The latter tally includes more than one-third of Republicans who disapprove of how their party’s congressional representatives are dealing with this.

Majorities of Americans say Democrats in Congress are making a necessary stand against Trump’s actions (61 percent) and are acting to uphold their constitutional duties (53 percent). Similarly, a majority (55 percent) say Democrats are not overreacting by starting the impeachment inquiry. However, in a potential warning sign to Democrats, 50 percent of Americans say that the impeachment proceeding is distracting Congress from more important issues, slightly higher than the percent who disagree (46 percent).

The survey finds cracks within the Republican coalition on the question of support for the impeachment inquiry, with younger and more moderate Republicans offering greater support. Overall, 25 percent of Republicans and Republican-leaning independents support the impeachment inquiry. Broken down by ideology, 41 percent of moderate-to-liberal Republicans say they favor the inquiry, compared with 16 percent of conservatives, who make up the majority of the party.

Broken down by age groups, 40 percent of Republican-leaning adults ages 18-39 endorse the start of the impeachment inquiry, compared with 23 percent of those ages 40-64 and 13 percent of those age 65 and older.

On the question of the appropriateness of Trump’s request to Zelensky to investigate Biden and his son, 45 percent of moderate-to-liberal Republicans and Republicans under age 40 say it was not appropriate. Overall, 33 percent of Republican-leaning adults say it was inappropriate.

As in many things related to the president, there is a significant gender gap in the findings of the poll, with 65 percent of women favoring the impeachment inquiry, compared with 51 percent of men.

A majority (61 percent) of white college graduates favor the inquiry, while whites without college degrees, a mainstay of Trump’s support, are split: 47 percent in favor and 48 percent in opposition. A smaller majority (53 percent) of white college graduates also say the House should recommend that the president be removed from office.

The poll was conducted by The Post and the Schar School of Policy and Government at George Mason University. The survey was administered by telephone Oct. 1-6 among a random national sample of 1,007 adults, 69 percent of whom were reached on cellphones and 31 percent on landlines. The margin of sampling error is plus or minus 3.5 percentage points; the error margin is larger for results among subgroups.