WASHINGTON, D.C. — Rep. Liz Cheney, the No. 3 Republican in the House, accused Donald Trump of “poisoning” U.S. democracy with his false election claims, escalating the GOP’s internal conflict over the former president’s role in the party.

She tweeted a response on Monday to a statement from Trump saying that the 2020 presidential election was fraudulent and should be “known as THE BIG LIE!”

Turning that phrase against him, Cheney said: “The 2020 presidential election was not stolen. Anyone who claims it was is spreading THE BIG LIE, turning their back on the rule of law, and poisoning our democratic system.”

Cheney, Wyoming’s sole representative in the House, and Trump have traded verbal broadsides since shortly after the Jan. 6 attack on the Capitol, which began after the then-president addressed a rally near the White House and encouraged his supporters to “fight like hell” and to march to Capitol Hill to oppose the certification of electoral college results.

She said in February that the Republican Party must acknowledge the damage done by Trump’s unfounded claims that the election had been stolen from him and his actions on Jan. 6, which led to his second impeachment.

Cheney, one of 10 House Republicans who voted to impeach the former president, has become increasingly isolated in her party over her repeated criticism of Trump. He has encouraged Wyoming Republicans to vote her out of office. After her tweet on Monday he issued a second statement, calling her a “warmonger” and predicting “she’ll never run in a Wyoming election again.”

Cheney, the daughter of former Vice President Dick Cheney, survived an attempt to oust her from her leadership post in early February, but Trump loyalists may try to raise the issue again.

Most other Republicans who had blamed Trump for stoking the mob that attacked the Capitol, including House GOP leader Kevin McCarthy, have since muted their criticism, as the former president continues to have a strong hold over many Republican voters.

“That’s a question for the conference,” McCarthy said last week after he was asked if Cheney was a “good fit” for the Republican conference in the House.

The No. 2 House Republican, Rep. Steve Scalise of Louisiana, when asked about Cheney in an interview with Axios on Friday said Trump “is still a very active part of our party” who helped turn out millions of voters for Republicans and is key to GOP hopes to retake the House.

“This idea that you just disregard President Trump is not where we are,” added Scalise, who with McCarthy was one of 147 Republicans in Congress who voted — after the riot — to contest the 2020 presidential election results.