WASHINGTON – Rep. Alexandria Ocasio-Cortez, D-N.Y., added further fuel to the impeachment fire in a Saturday evening tweet where she said the even bigger scandal than the controversy over Biden, Ukraine, and the Trump-Congress whistleblower fight was House Democrats' refusal to impeach Trump.

"At this point, the bigger national scandal isn't the president's lawbreaking behavior - it is the Democratic Party's refusal to impeach him for it," she wrote.

Although House Speaker Nancy Pelosi still opposes impeachment, it appears that the controversy is starting to shift the calculus for some Democrats.

Rep. Adam Schiff, D-Calif., the chair of the House Intelligence Committee, said in a Sunday morning television interview, "we very well may have crossed the Rubicon here.”

"If the president is essentially withholding military aid at the same time he is trying to browbeat a foreign leader into doing something illicit...then [impeachment] might be the only remedy that is co-equal to the evil that this conduct represents," he said on CNN's "State of the Union."

At this point, the bigger national scandal isn’t the president’s lawbreaking behavior - it is the Democratic Party’s refusal to impeach him for it. — Alexandria Ocasio-Cortez (@AOC) September 22, 2019

The growing controversy surrounds an August whistleblower complaint by a U.S. intelligence community official and ongoing efforts by Democrats to learn more about Trump's contacts with Ukraine. Democrats have demanded access to the whistleblower complaint.

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Trump acknowledged he had discussed an investigation into Biden with the Ukrainian president while speaking with reporters en route to a trip to Texas and Ohio on Sunday morning.

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Trump said: "The conversation I had was largely congratulatory, with largely corruption – all of the corruption taking place – and largely the fact that we don't want our people like Vice President Biden and his son creating to the corruption already in the Ukraine."

He described the call as "absolutely perfect."

More: What's going on with Biden and Ukraine? And how does it involve the Trump-Congress whistleblower fight?

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On Fox News on Sunday morning, congressional Republicans called for investigations of their own and denounced the drive for impeachment as a goal of "socialists."

Sen. Lindsey Graham, R-S.C., said on Fox News' "Sunday Morning Futures" that he wanted the Department of Justice to "appoint an investigator to look at all things Ukraine" and what he said the Ukrainian government had done to help Democrats in the 2016 election.

And later in the show, Rep. Devin Nunes, R-Calif., who is the top Republican on the House Intelligence Committee, accused Ocasio-Cortez of promoting a "socialist" agenda of "one-party control" of government.

"The more I think that they’re out there promoting this kind of craziness and silliness, the more that the American people are put off, and the more likely President Trump is re-elected,” Nunes added.

Contributing: Bart Jansen, Michael Collins, David Jackson

This article originally appeared on USA TODAY: AOC says bigger scandal than Ukraine is Dem's refusal to impeach Trump