A new Hill-HarrisX survey on Friday found support for impeachment proceedings against President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE has risen 12 points compared to a similar poll conducted three months ago.

The survey was conducted on Sept. 26-27, just days after House Democrats started a formal impeachment inquiry over a whistleblower complaint involving Trump’s communications with Ukraine.

The poll showed 47 percent of respondents support that decision, up 12 points from a similar survey in June, which asked whether Democrats should begin impeachment proceedings.

Meanwhile, opposition to impeachment dipped 3 points to 42 percent, while 11 percent of those polled in the new survey said they weren't sure or didn't know.

Support for impeachment grew among Democratic, Republican and independent voters alike. Democratic support jumped from 59 percent to 78 percent, a 19-point increase. The number of Republicans backing impeachment jumped 5 points to 18 percent.

The number of independents who back impeachment doubled to 41 percent.

The House Intelligence Committee on Thursday released a a declassified version of a whistleblower’s complaint detailing Trump’s July 25 call with Ukraine President Volodymyr Zelensky.

The whistleblower, who is believed to be a former CIA official, alleges that Trump tried to persuade Zelensky to launch an investigation into former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE and his son Hunter Biden to help boast Trump's reelection chances in 2020.

Trump has repeatedly denied any wrongdoing and the party has largely come to the president's defense.

The White House had earlier released a partial transcript of the call, which came days after Trump delayed hundreds of millions of dollars in U.S. aid to Ukraine. Trump does not explicitly mention a quid pro quo with Zelensky in the White House memo, though he does segue from a discussion of military assistance to the potential Biden probe.

The Hill-HarrisX survey surveyed among 1,001 voters and the margin of error was 3.1 percentage points.

—Tess Bonn