The movement to remove President Donald Trump from office gained a critical ally this week, when Rep. Ben Ray Lujan announced his support for an impeachment inquiry.

Lujan is a close ally of House Speaker Nancy Pelosi and is the most high profile Democrat to back impeachment so far.

More than half of House Democrats now support impeaching or launching an impeachment inquiry against Trump. And since Congress broke for recess last month, more than two dozen Democrats came out and announced their support for the measure.

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The push to remove President Donald Trump from office gained a critical ally this week when Rep. Ben Ray Lujan announced his support for an impeachment inquiry.

Lujan is the fourth highest-ranking House Democrat and a close ally of House Speaker Nancy Pelosi. He is the most high-profile Democrat to back impeachment so far, and he was instrumental in getting many freshman Democrats elected, according to Politico. For that reason, his support for the measure could be the catalyst for younger, newer members of Congress to back it, too.

More than half of House Democrats support impeaching or launching impeachment proceedings against Trump. Lujan is the 127th House Democrat to back it, while 108 Democrats are against it, including Pelosi and several other establishment lawmakers.

Lujan, who is running for an open Senate seat in New Mexico next year, said his decision to back impeachment proceedings was influenced by the former special counsel Robert Mueller's report in the Russia investigation.

"President Trump's lack of action is jeopardizing our elections, national security, and Democracy," Lujan said. "Not only has he ignored the warnings that our Democracy is being targeted, but he has also actively encouraged Russian interference."

A senior Lujan aide told the Washington Post that the lawmaker has backed an impeachment inquiry for a while but didn't want to get out in front of moderate House Democrats he helped elect last year. "Now was just the right time," the aide said.

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The question of whether or not to impeach the president after the release of the Mueller report has driven a wedge between congressional Democrats. Pelosi is pushing back on calls for impeachment, arguing that it would be too politically divisive.

Instead, she says the six Democrat-led investigative committees in the House should continue their sprawling inquiries into Trump's administration, finances, business dealings, campaign, inaugural committee, and more.

But the House speaker is fighting an uphill battle against Democrats like New York Rep. Jerry Nadler, the chairman of the House Judiciary Committee who told CNN this month that the panel is already conducting a formal impeachment inquiry.

"We are investigating all the evidence, gathering the evidence," Nadler said. "And we will [at the] conclusion of this — hopefully by the end of the year — vote to vote articles of impeachment to the House floor. Or we won't. That's a decision that we'll have to make. But that's exactly the process we're in right now."

A protracted battle

The House Intelligence Committee is also playing a key, unprecedented role in Nadler's impeachment investigation, Politico reported, because of the nature of Mueller's findings in the Russia probe.

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Broadly, Mueller's probe consisted of two prongs: a counterintelligence investigation examining Russia's interference in the 2016 election, and a criminal investigation looking at whether Trump obstructed justice after then-FBI Director James Comey publicly confirmed the investigation's existence in March 2017.

While Nadler's panel has focused largely on the obstruction case, House Intelligence Committee Chairman Adam Schiff has signaled a keener interest in Mueller's counterintelligence findings, namely Trump's encouragement of Russia's interference in the 2016 race, and his company's efforts to build a Trump Tower in Moscow at the time.

As the head of the intelligence panel, Schiff has greater access to classified material, much of which was contained in Mueller's counterintelligence probe. And a source close to the California lawmaker told Politico that in a case as unique as Trump's, "it is important to consider the totality of the evidence, including classified information."

Last month, Nadler's committee filed a legal request for a federal judge to release grand-jury information from Mueller's investigation, which was excluded from the version of his final report that the Justice Department released to Congress and the public.

In the filing, House lawyers argued that the judiciary and intelligence committees want to review grand jury materials as Nadler's panel assesses "whether to recommend articles of impeachment against the president."

Since the judiciary committee made the request, more than two dozen Democrats have come out and publicly voiced their support for an impeachment inquiry.

But practically, the path forward is a bit murkier. Nadler's committee is in a protracted battle with the White House over obtaining documents and getting witnesses to testify to lawmakers about Trump's actions during the campaign and after he took office.

And it's unclear how the committee will proceed once Congress gets back from recess: will it began drawing up articles of impeachment against Trump, or will it continue duking it out with the administration over documents and witness testimony?

Democratic aides told the Post they aren't sure where things go from here either.