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Vice President Mike Pence sought to rally conservatives for the fight to repeal and replace ObamaCare Thursday, telling a fired-up CPAC audience that the health care law "has failed" and "must go."

"Let me assure you," Pence told the cheering crowd. "America’s ObamaCare nightmare is about to end."

"This failed law is crippling the American economy and crushing the American people," added Pence, who called promises made by liberals about former president Obama's health reform "fake news."

"Now we all know the truth," the vice president said. "Higher costs, fewer choices, worse care. That's ObamaCare."

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Pence vowed that ObamaCare would be replaced with "something that actually works, something that's built on freedom and individual responsibility." He promised "an orderly transition to a better health care system" and repeated Trump's campaign vow that any new healthcare law would allow the purchase of insurance across state lines and ensure that customers with pre-existing conditions would be covered.

Pence did not offer a timetable for any new legislation. Another CPAC speaker, former South Carolina Sen. Jim DeMint, called earlier Thursday for the immediate dismantling of the 2010 health care law, saying the argument that a replacement plan must also be in place is “ludicrous.”

Pence's speech capped the first day of the annual conference, during which President Donald Trump's top aides warned activists not to waste GOP control of the White House and both houses of Congress.

"We as conservatives have an opportunity that only comes around every few generations, or maybe just once in a lifetime," Pence said. "My friends, this is our time."

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Referencing the turbulent town halls that have greeted Republican lawmakers during the congressional recess, Pence urged CPAC attendees to "rise to the challenge before us."

"The other side is not sitting idle," the vice president warned before telling his audience to "mobilize" and "march foward" to defend Trump's agenda.

"Our fight didn’t end on [Election Day]," Pence said. "We won the day, but make no mistake about it. The harder work, the most important work, now lies ahead."

FoxNews.com's Joseph Weber and the Associated Press contributed to this report.