A plurality of Americans now support impeaching Trump and removing him from office.

The partisan divide is huge: 74% of Democrats but just 17% of Republicans back impeachment.

By 2-1, those surveyed say there are valid reasons to investigate Joe Biden and his son for their behavior in Ukraine.

Americans by a 45%-38% plurality now support a vote by the House of Representatives to impeach President Donald Trump, a USA TODAY/Ipsos Poll finds, as allegations continue to swirl around an embattled White House.

By a similar margin, 44%-35%, those surveyed say the Senate, which would then be charged with holding a trial of the president, should convict Trump and remove him from office.

The survey of 1,006 adults, taken Tuesday and Wednesday, underscores the perilous situation the president finds himself in as House committees subpoena documents and prepare to hear testimony into accusations that he pressured the leader of Ukraine to investigate a political rival, then tried to hide the account of their phone conversation.

Trump, who has released a rough transcript of his July 25 call with the president of Ukraine, says the conversation was "perfect" and that there was no wrongdoing. On Tuesday, he lashed out during a White House news conference, referring to the inquiry as a "hoax."

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Americans have long been wary of impeachment. A USA TODAY/Suffolk University Poll taken in June – months before the formal impeachment inquiry was launched last week – found opponents outweighing supporters by nearly 2 to 1, 61%-32%.

But several national surveys have shown attitudes significantly shifting in the past 10 days, since the latest allegations emerged about Ukraine and House Speaker Nancy Pelosi announced the impeachment inquiry.

“Our latest USA TODAY/Ipsos poll shows that public support for impeachment continues to build with a plurality – 45% – saying the U.S. House should vote to impeach,” said Cliff Young, president of Ipsos Public Affairs. “Most importantly, an overwhelming majority of Americans say that a president is subject to laws like any citizen. Public opinion might be tolerant, but there are limits.”

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Impeach? A huge partisan divide

The question of impeachment opens a huge partisan divide. Among Democrats, 74% in the new USA TODAY/Ipsos poll support impeachment; just 17% of Republicans agree. Independents are split down the middle, 37%-37%.

Even among Republicans, however, 30% say the president asking Ukraine to look into the behavior of former vice president Joe Biden and his son, Hunter, would be an abuse of power. And 80% of Republicans – a higher number than among Democrats or independents – say the president is subject to all laws, just like any other citizen.

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One more warning sign for Trump: Nearly two-thirds of Republicans say there isn't enough reliable information to decide whether he should be impeached. That leaves open the possibility that dramatic disclosures and persuasive evidence could convince some in Trump's own party that impeachment is warranted.

Democrats are more likely to say they already know enough; just 15% say there isn't enough evidence so far.

The survey includes some cautionary notes as well for Biden, the Democratic front-runner for the presidential nomination to challenge Trump next year. By 2 to 1, 42%-21%, those polled say there are valid reasons to look at the behavior of Joe and Hunter Biden in Ukraine. Even 1 in 4 Democrats say an investigation would be legitimate; two-thirds of Republicans agree. Joe Biden was the Obama administration's point person on Ukraine; his son pursued lucrative business arrangements there.

There has been no evidence of wrongdoing by either Biden, though Trump on Wednesday accused them both of being corrupt.

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That said, the poll found a broad bipartisan consensus, including more than 6 in 10 Republicans and Democrats, that the children of senior officials should be prohibited from benefiting from their family relationships.

While often not illegal, the perception of self-dealing and conflicts of interest have long fueled voter distrust of government and its leaders. Critics have charged that Trump's children and his business empire have used his position for financial gain.

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Whistleblower: A patriot or traitor?

In the poll, views were mixed about the whistleblower who originally reported concerns about Trump's phone call with the Ukrainian president. Seventy-one percent of Democrats call that person "a patriot"; just 10% call him or her "a traitor," a label Trump has used. The president hasn't yet convinced a majority of members of his own party that the description fits, though.

Among Republicans, 36% call the whistleblower "a traitor," but 21% say he or she is a patriot. The largest number, 43%, say they don't know.

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A majority of Americans are knowledgeable about some of the particulars of the impeachment process: 56% know that impeachment begins in the House; 55% know that an impeachment vote in itself doesn't remove a president from office; 62% know that a two-thirds majority in the Senate would be needed to do that.

However, most Americans don't realize that would be an unprecedented step. Fifty-one percent say American presidents have been removed from office by impeachment in the past. While two presidents have been impeached by the House, neither Andrew Johnson nor Bill Clinton was convicted by the Senate. A third president, Richard Nixon, resigned in the face of near-certain impeachment and conviction.

Few Americans, just 3%, predict that Trump will voluntarily resign before the end of his first term; 15% expect him to be removed through impeachment. One-third of those surveyed, 33%, say he will remain serve out his first term as president. Another 29% predict that he will not only do that but also win a second term.

The online poll has a credibility interval of plus or minus 3.5 percentage points.

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