U.S. House Speaker Nancy Pelosi painted herself as a once-reluctant but now fully engaged general amid her party's push for an impeachment inquiry, in an onstage interview at The Texas Tribune Festival on Saturday.

To make her point, she used sweeping, solemn language to underscore her view that what is happening at the U.S. Capitol is an existential moment in American history.

"If this activity, this pattern of behavior were to prevail ... then it's over for the republic," she said. "We will have the equivalent of a monarchy."

"Let us be prayerful. Let us be solemn. Let us try not to make it further divisive," she added. "But we cannot ignore our oath of office to defend the Constitution of the United States from all enemies foreign and domestic."

In her most extensive interview about impeachment since she announced plans to open an inquiry this week, Pelosi described herself as "heartbroken" over the revelation that President Donald Trump asked the Ukrainian president to investigate former Vice President Joe Biden's son, Hunter Biden. White House disclosures of the conversation — and that Trump withheld military aid from Ukraine prior to the conversation — unleashed a firestorm in Washington last week.

"I think right now there is a cover-up of a cover-up," she said.

When asked why she moved from the strongest backstop against impeachment to the leader of the effort, she chose brevity: "The facts."

"I have handled this with great care, with moderation, with great attention to what we knew was a fact and what was an allegation.

"This is very bad news for our country because if — as it seems to be — our president has engaged in something that is so far beyond what our founders had in mind they knew that some president might go beyond what the Constitution intended."

Pelosi has long prided her experience dating back to her rank-and-file days as a member of the House Intelligence Committee.

"I'm saying to the president and I'm saying to you, 'You've come into my wheelhouse now. I have 25 years of experience in intelligence,'" she said.

When asked by interviewer Evan Smith, CEO and co-founder of The Texas Tribune, how the impeachment will play politically, she replied: "That doesn't matter. That doesn't matter."

But she added that she remained confident that her party would maintain control in the House in 2020.

She warned her colleagues against ever using impeachment to settle policy differences with a president. She gave no indication how long the inquiry would take, and several times Pelosi indicated that there were no foregone conclusions that the House would deliver an impeachment for trial in the U.S. Senate.

"Nancy Pelosi is more interested in her baseless impeachment threat than she is in doing her job and passing the [United States-Mexico-Canada Agreement], addressing the humanitarian crisis at the border, and working with President Trump," Trump campaign spokeswoman Samantha Cotten said in response to Pelosi's comments. "Texans realize that Nancy Pelosi is just another coastal elite committed to obstructing President Trump at every turn."

On other topics, Pelosi said before the party goes on full offense in Texas, the focus should be on reelecting U.S. Reps. Colin Allred of Dallas and Lizzie Pannill Fletcher of Houston. She was also bullish on former Air Force Intelligence officer Gina Ortiz Jones' odds of winning the Texas 23rd District, which is currently held by retiring U.S. Rep. Will Hurd, R-Helotes, and she reiterated her support for U.S Rep. Henry Cuellar, D-Laredo, who is facing a primary challenge from the left. Her comments on Cuellar, were met with scattered boos in the audience.

As for policy, she said that her priority prior to the escalation of impeachment was working to prevent gun violence. She did say later in the discussion that she would not support a mandatory buy back program for assault weapons. Instead, she impressed upon Democrats to keep their "eyes on the prize" and focus on policies that had a better chance of passage, including background checks.

Even amid the grim moment, Pelosi flashed signs of humor and sarcasm. She declined to endorse in the current presidential primary.

"I don't get involved in presidential races," she said. "I have enough to deal with in the House."

And when a woman heckled her from the audience, Pelosi shrugged it off.

"I'm speaker of the House," she said. "I'm used to this."

Chase Karacostas contributed to this report.