Sizable minorities of Americans think that President Trump’s campaign colluded with the Russians to help him win the 2016 election and that President Barack Obama spied on the Trump campaign, according to a new Washington Post-ABC News poll.

Views of both claims being investigated by Congress are colored dramatically by party affiliation and how one voted in the election between Trump and Hillary Clinton, the poll found, with Democrats far more likely to see collusion and Republicans to see spying.

Half of the public, meanwhile, says they are not confident that Congress will conduct a fair investigation into Russia’s role in last year’s election, with significant doubts crossing party lines.

Questions about Russia’s meddling in the election have dogged Trump since he took office in January, and last month FBI Director James B. Comey told Congress that his agency is conducting an investigation into possible coordination between the Kremlin and the Trump campaign.

Trump sparked a new controversy in early March with accusations on Twitter that Obama had wiretapped his phones in Trump Tower in New York. Intelligence and law enforcement officials have said there is no evidence to support Trump’s claim.

The poll underscores the extent to which a partisan lens can affect the way Americans view the same set of facts.

Overall, nearly 4 in 10 Americans think some members of Trump’s campaign helped the Russian government influence the election.

The partisan divide on the question is stark: About 6 in 10 Democrats say Russia tried to sway the election with the help of the Trump campaign, while only about 1 in 10 Republicans say that is the case.

Meanwhile, about one-third of Americans think the Obama administration intentionally spied on Trump and members of his campaign during the 2016 election.

There is a sharp partisan divide here, too: Just over half of Republicans believe there was improper surveillance, while only about 1 in 10 Democrats say that was the case.

The differences in views on both issues are even more dramatic between Americans who voted for Clinton and those who voted for Trump. Clinton voters are 68 percentage points more likely than Trump voters to say the president colluded with Russians, while Trump voters are 54 points more likely than Clinton voters to say Obama spied.

Gary Phillips, 65, a Trump supporter who lives in Conneaut, Ohio, is among those who say Obama spied on the Trump campaign.

“I wouldn’t put it past the Obama bunch,” said Phillips, a retiree who previously managed a private lake in his state, when asked why he believes the claim.

Phillips also expressed a general disdain for Obama and said he has often been untruthful.

“I wouldn’t believe him if he said today was sunny or today was cloudy,” Phillips said.

Meanwhile, Sam Hassan, 27, a stay-at-home mom and registered Democrat in Dracut, Mass., is convinced Trump colluded with the Russians in last year’s election.

“I find it very ironic that he asked them to do some sort of hacking into Hillary Clinton’s email and then WikiLeaks leaks out all sorts of her email,” Hassan said.

She was referring to a July news conference at which Trump urged Russia to help find 30,000 emails he said were missing from a private server that Clinton used as secretary of state. WikiLeaks is the organization that published thousands of hacked emails of John Podesta, Clinton’s campaign chairman, that were kept on a different server.

Hassan said she has no confidence in the Republican-led probes in the House and the Senate to get to the bottom of alleged meddling in the U.S. election by the Russian government.

“It’s Trump’s people who are working on the investigation,” she said. “It’s clear nothing is going to be found.”

Both the House and Senate investigations have drawn criticism in recent weeks.

House Intelligence Committee Chairman Devin Nunes (R-Calif.) recused himself from the Russian probe amid criticism that he was too friendly with a White House he was tasked with investigating. Those accusations followed a Nunes briefing of Trump at the White House on documents Nunes had not shared with others on the committee, including its ranking Democrat.

The Senate Intelligence Committee has more recently drawn flak for the pace at which it is proceeding.

The Senate Judiciary Committee announced Tuesday that it would hold a public hearing next month on Russian interference that will include as witnesses Sally Yates, the former acting attorney general, and James R. Clapper Jr., the former director of national intelligence.

The Post-ABC poll found 42 percent saying they are confident Congress will conduct a fair investigation while 50 percent are not. Four in 10 Republicans say they doubt the investigation’s fairness, rising to 51 percent among Democrats and 58 percent among political independents.

While no conclusive evidence has emerged that Trump colluded with the Russians, the FBI and U.S. intelligence agencies have stated emphatically that Russia sought to undermine the 2016 election and sway it in Trump’s favor — a finding most leading Republicans in Congress have accepted. Several have called for additional sanctions on Russia in retaliation.

A 56 percent majority of Americans believe the Russian government tried to influence the U.S. election, while 35 percent say it did not and 9 percent have no opinion.

More than 7 in 10 Democrats said they think there was meddling, while just over 3 in 10 Republicans said there was and 6 in 10 independents believe Russia interfered.

Among Trump voters, 28 percent say Russia attempted to influence the fall election compared with 83 percent of Clinton voters who say the same.

Among those with postgraduate degrees, 7 in 10 said Russia tried to interfere with the election, while just over half of those with a high school education or less said that was the case.

The poll also found that those who think Russia tried to influence the election are less confident in the ability of Congress to fairly investigate. Sixty-two percent of those who think Russia interfered are not confident Congress will investigate fairly. That compares with 50 percent of Americans overall.

The Post-ABC poll was conducted April 17-20 among a random national sample of 1,004 adults interviewed on cellular and landline phones. Overall results have a margin of sampling error of plus or minus 3.5 percentage points.

Scott Clement contributed to this report.