Rep. Zoe Lofgren, then congressional staffer during the Watergate era, is seen at the US Capitol circa 1974. Lofgren worked for then-Rep. Don Edwards, a member of the House Judiciary committee
CNN  — 

When she walks through the Senate chamber on Wednesday to present her case for removing President Donald Trump from office, Rep. Zoe Lofgren could be forgiven for having a sense of deja vu.

Of all the seven House impeachment managers prosecuting the President, Lofgren has the most practice. The California Democrat, 72, is the only member of the House and Senate involved in the three impeachment investigations of the modern era, serving as a staffer to Rep. Don Edwards, a member of the House Judiciary committee, in 1974, before being elected to the same seat two decades later.

Lofgren has proved an invaluable resource to her fellow Democrats, who view her first-hand perspective to the Richard Nixon and Bill Clinton impeachments as a major asset going into the Senate trial.

Zoe Lofgren speaks during a news conference surrounded by fellow House Democrats after the impeachment inquiry vote for then-President Bill Clinton in October 1998.

“Congresswoman Zoe Lofgren brings incredible institutional history and knowledge to our group of House impeachment managers,” Rep. Sylvia Garcia, a first-term member from Texas, told CNN. “I will certainly be leaning on her wisdom and expertise as we make the case to the American people.”

Sen. Pat Leahy, the longest-serving Democrat in the chamber, added Lofgren brings “a lot of experience – and integrity.”

In an interview in December, Lofgren said she has advised younger Democratic members to “familiarize themselves” with historical precedent and recommended a ’74 report on the origins of impeachment and the Constitution’s meaning of high crimes and misdemeanors.

“It’s not just whatever you think,” Lofgren said. “We are the product of our history and we should be creatures of our law – the most important of which is the Constitution.”

Lofgren is seen speaking from the House floor on Tuesday.

On Tuesday, Lofgren became the first woman to speak on the Senate floor as an impeachment manager, pressing to change the rules of the trial to allow the prosecution to subpoena records and witnesses. She recalled her experience going through boxes of papers during the 1999 Clinton impeachment trial and argued that Trump’s refusal to produce documents in response to congressional subpoenas was different than Clinton, Andrew Johnson and “even” Nixon, who resigned before the House could impeach him.

“Not a single president has issued a blanket direction to his administration to produce no documents and no witnesses,” Lofgren said.

Republicans voted to table the Democrats’ amendment, but a small core of Republicans may support subpoenaing witnesses and documents later, like in the Clinton trial.

Lofgren offers not only an unmatched familiarity with how to investigate the president but the authority of a Democrat who did not publicly support one into Trump until the Ukraine scandal came to light.

Unlike some other managers, Lofgren did not push to build a case for impeachment after special counsel Robert Mueller released his report on Russian interference in the 2016 campaign and the President’s efforts to thwart his probe. Instead she, like House Speaker Nancy Pelosi, urged the media to cover legislation that the Democratic-controlled House passed, like a bill to provide legal protections for the so-called recipients of the Deferred Action for Childhood Arrivals program who illegally came to the country as children. While that may not have been enough for some Democrats in her safe, southern San Jose district, it fit her role as the top Democrat on the Judiciary’s subcommittee regarding immigration and border security.

But Lofgren, and almost all of the House Democrats, supported an impeachment inquiry after learning of reports that Trump used his office to pressure Ukraine to announce an investigation to damage his political rival, former Vice President Joe Biden.

Over Thanksgiving, she reviewed documents related to the inquiry while taking the time to prepare the stuffing and cook a 34-pound turkey for her family. Her sister-in-law came a day early, and her children pitched in to help.

“It was a group effort,” she said. A few weeks later, she voted to impeach Trump on two charges: abuse of power and obstruction of Congress.

White House counsel Pat Cipollone argued Tuesday that Trump had done nothing wrong. In its brief, the defense team said that the prosecution has broken with prior impeachments in not basing their violations on criminal law, since the House Judiciary committee voted to impeach Nixon on obstruction of justice and Clinton on that and perjury.

House Democrats have defended their choices, even though some claimed that Mueller described other impeachable offenses like obstruction of justice.

In December, Lofgren told CNN that the House was “prohibited” from accessing documents and witness testimony related to the potential obstruction described in the report and were on “firmer ground” proceeding only with articles where Democrats had “direct evidence.”

“I do think that he has committed a serious violation of his oath of office,” Lofgren told CNN. “He has abused his power to the detriment of the United States and he’s also failed in his duty to provide information to the Congress.”

“That’s a stain on his presidency,” she added.