WASHINGTON (AP) — Democrats pushed a package of ground rules for their impeachment inquiry of President Donald Trump toward certain House passage on Thursday as the chamber passed the first formal vote on an epic clash that could well stretch into next year.

Each side was expected to lose a handful of defectors, if any. The rules outline how the last several weeks of closed-door depositions of witnesses by three House committees would transition into public hearings and, ultimately, a vote by the House Judiciary Committee.

“If we don’t hold this president accountable, we could be ceding our ability to hold any president accountable,” said Rep. James McGovern, D-Mass., chairman of the House Rules Committee.

Democrats said the procedures — which give them the ability to curb the president’s lawyers from calling witnesses — are similar to rules used during the impeachment proceedings of Presidents Richard Nixon and Bill Clinton. Republicans complained they were skewed against Trump.

“It’s not fair to the president of the United States, it’s not fair to the House of Representatives, it’s not fair to the American people,” said Rep. Tom Cole, R-Okla.

The investigation is focused on Trump’s efforts to push Ukraine to investigate his Democratic political opponents by withholding military aid and an Oval Office meeting craved by the country’s new president.

It is likely to take weeks or more before the House votes on whether to actually impeach Trump. If the House impeaches Trump, the Senate would hold a trial to decide whether to remove him from office.

Both parties’ leaders were rounding up votes as Thursday’s roll call approached, with each side eager to come as close to unanimity as possible.

Republicans said a solid GOP “no” vote would signal to the Senate that the Democratic push is a partisan crusade against a president they have never liked. House Minority Leader Kevin McCarthy, R-Calif., said he’s unaware of any Republican even “leaning toward voting for it.”

Democrats were also hoping to demonstrate solidarity from their most liberal elements to their most moderate members. They argued that GOP cohesion against the measure would show that Republicans are blindly defending Trump, whatever facts emerge.

“It will show the other party has become the party of Trump. It’s really not the Republican Party any longer,” said Rep. Dan Kildee, D-Mich.

Democrats’ chief vote counter, Rep. James Clyburn of South Carolina, said he believed “less than half a dozen” from his party would oppose the package.

Republicans said they’d use the vote to target freshman Democrats and those from districts Trump carried in 2016. They said they would contrast their support for the rules with campaign promises to focus on issues voters want to address, not on impeaching Trump.

The House GOP’s campaign arm sent emails to reporters all but taunting some of those Democrats including freshman Rep. Chris Pappas, D-N.H. “Pappas wants to be a one-termer,” one said.

GOP leaders called the rules “Speaker Pelosi’s sham process designed to discredit the Democratic process” in their daily impeachment email to lawmakers.

House Speaker Nancy Pelosi, D-Calif., decided to have the vote following weeks of GOP claims that the inquiry was invalid because the chamber had not voted to formally commence the work.

The rules lay out how the House Intelligence Committee — now leading the investigation by deposing diplomats and other officials behind closed doors — would transition to public hearings.

That panel would issue a report and release transcripts of the closed-door interviews it has been conducting with diplomats and other officials with connections to Trump’s interactions with Ukraine.

The Judiciary Committee would then decide whether to recommend that the House impeach Trump — a finding that he should be removed from office.

Republicans could only issue subpoenas for witnesses to appear if the entire panel approved them — in effect giving Democrats veto power over such requests by the GOP.

Attorneys for Trump could participate in the Judiciary Committee proceedings. But in a bid for leverage, panel Chairman Jerrold Nadler, D-N.Y., would be allowed to deny “specific requests” by Trump representatives if the White House continues refusing to provide documents or witnesses sought by Democratic investigators.