Republicans dominating a nearly half-empty North Carolina House chamber used an unexpected vote Wednesday to override Democratic Governor Roy Cooper's veto of the state's two-year budget, prompting accusations of trickery and deception from Cooper and other Democrats, many of whom were attending 9/11 commemoration events during the sudden vote.

Republican leaders had spent months trying to persuade enough Democrats to meet the threshold for an override, and finally seized a moment when most opposing Democrats weren't at their seats. The few Democrats who were on the House floor moments before the 55-9 vote erupted in protest, accusing Republican Speaker Tim Moore of tricking the chamber about the day's plans.

According to reporting by local station ABC 11, many Democrats were at 9/11 commemoration events. House Democrats charge that Republicans had deliberately misled them by saying there would be no votes on the morning of 9/11. ABC 11 reporter Jonah Kaplan posted the schedule sent by the Democratic minority leader to his caucus, confirming that there were no votes scheduled until 1 p.m.

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The override isn't complete — the Senate still must hold a vote on the issue, but Republicans there need only one Democrat to join them to secure victory. Senate absences also could make that easier.

"This is a tragedy. This is a travesty of the process and you know it," State Representative Deb Butler, a New Hanover County Democrat, yelled at Moore just before the vote began. "Mr. Speaker, how dare you, Mr. Speaker!"

Moore told her that he "did not advise that there would be no votes this morning." Moore's office provided audio from Tuesday's floor session from House Rules Committee Chairman David Lewis saying recorded votes would occur Wednesday, specifically identifying two different spending measures.

Still, in a fiery early-afternoon news conference, Cooper maintained that Democrats had been misled.

"You look at the number of people who were in that chamber and how many of them were Republicans and how many of them were Democrats. There's no confusion about what happened here. This was a lie, and we know why they were not there because they were told that there were not going to be votes," Cooper said. "And the Republican caucus was laying in wait, ready for this."

"They used lies, bribes and illegal districts because their policies damage our state and can't pass on their own merit. Today, on the 18th anniversary of 9/11, while the state was honoring first responders, Republicans called a deceptive surprise override of my budget veto," Cooper said.

However, Republican Jason Saine, who called for the motion to vote, claimed that the GOP House members were fulfilling their patriotic duties by holding the vote.

"As a former firefighter and an American, I am appalled that anyone in our country would stop going about their normal business on this day. When we stop being a beacon of freedom, hope and democracy, then the terrorists win," Saine said in a statement, according to ABC 11.

It wasn't immediately clear how many Democratic lawmakers may have been attending memorials during the vote.

The House budget override vote has been on the daily floor calendar since early July, and from time to time the Republican leadership had announced that there would be no recorded votes on certain days. There was nothing in the chamber rules to prevent such action Wednesday.

Wednesday's vote also came as lawmakers focus on redrawing legislative maps following a court ruling striking down dozens of districts due to extreme partisan bias.

It also marks the latest battle in a decade-long fight between Republicans who took over the General Assembly in 2011 and Democrats whose party had largely controlled state government for over a century. Democrats have regained some power with Cooper's election in 2016, and ended the GOP supermajority in the House last year by gaining enough legislative seats to prevent veto overrides when the chamber is full.

Cooper vetoed the budget on June 28, saying the two-year spending plan lacks Medicaid expansion for hundreds of thousands of low-income adults, contains paltry raises for teachers and unnecessarily gives corporations additional tax reductions. The veto and lack of an override had led to an 11-week budget impasse. Republicans have said Cooper won't negotiate unless Medicaid expansion is approved, too. Cooper said he just wants the topic to be on the table.

Wednesday's vote was called quickly, giving dozens of Democrats little time to reach the floor. House Minority Leader Darren Jackson of Wake County also said that several Democrats who were on the floor didn't vote and were denied the chance to debate the measure.

Moore "kept talking over us. He turned off our mics," State Representative Mary Belk, a Mecklenburg County Democrat, said at a news conference. She and others went to other desks to use the microphones. As Butler and others continued to blast Moore's actions from the floor, the speaker threatened that he could order Butler removed. Several Capitol police officers entered the chamber, and Democratic lawmakers surrounded Butler, who refused to yield.

"The unseemly lack of leadership is incredible, absolutely cowardice, childishness," Butler said as Moore called for an override vote, on a separate Cooper veto, which also succeeded. That funding measure is needed to prepare for North Carolina's forthcoming shift to a Medicaid managed-care system. It doesn't contain any Medicaid expansion provisions, but Cooper said in his veto message that health care policy should be done comprehensively — a likely reference to expansion.