Sen. Tammy Duckworth: I swore an oath to the Constitution, not to clap when Trump demands

We don't live in a dictatorship or a monarchy. I swore an oath—in the military and in the Senate—to preserve, protect and defend the Constitution of the United States, not to mindlessly cater to the whims of Cadet Bone Spurs and clap when he demands I clap

— Tammy Duckworth (@SenDuckworth)

WASHINGTO> - Sen. Tammy Duckworth, who has emerged in recent weeks as one of President Donald Trump's most vocal critics, fired back after Trump called Democrats "treasonous" for not applauding him during his State of the Union address.

"We don't live in a dictatorship or monarchy. I swore an oath - in the military and in the Senate - to preserve, protect and defend the Constitution of the United States, not to mindlessly cater to the whims of Cadet Bone Spurs and clap when he demands I clap," Duckworth wrote in a tweet, using a nickname she had given Trump, who had said in previous interviews that he was granted medical deferment during the Vietnam War after he was diagnosed with bone spurs in his feet.

Duckworth, D-Ill., who lost both legs in 2004 while serving in Iraq as an Army helicopter pilot, then shared this quote from Theodore Roosevelt, from an opinion piece the former president wrote during World War I: "To announce that there must be no criticism of the president or that we are to stand by the president, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public."

Duckworth has been highly critical of Trump, particularly on issues involving military and national security.

In a Senate-floor speech last month, Duckworth called Trump a "five-deferment draft dodger" who had no business accusing Democrats - like herself - of not caring for the military.

"Does he even know that there are service members who are in harm's way right now, watching him, looking for their commander in chief to show leadership, rather than to try to deflect blame?" Duckworth said.

The speech was prompted by a tweet in which Trump accused Democrats of "holding our Military hostage over their desire to have unchecked illegal immigration." It's one of many partisan attacks Trump launched to blame Democrats for a congressional budget stalemate that had led to a partial federal government shutdown.

The junior senator also accused Trump of trying to bait North Korea into a war by escalating his rhetoric against Kim Jong Un.

"I have a message for 'Cadet Bone Spurs,'" Duckworth said. "If you cared about our military, you'd stop baiting Kim Jong Un into a war that could put 85,000 American troops, and millions of innocent civilians, in danger."

During a speech about tax cuts Monday, Trump veered off script and accused Democrats of treason, a crime punishable by death, for not applauding even as he touted positive unemployment numbers during his State of the Union address

"Even on positive news like that, really positive news like that, they were like death and un-American," Trump told a crowd in Blue Ash, Ohio. "Somebody said 'treasonous.' I mean, yeah, I guess, why not? Shall we call that treason? Why not? I mean, they certainly didn't seem to love our country very much."

Responding to criticisms Tuesday, White House spokesman Hogan Gidley told NBC News that Trump was speaking "tongue in cheek" and was simply saying that all Americans, regardless of party, should celebrate positive news.

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Amy B Wang and John Wagner contributed to this article.