KING OF PRUSSIA, Pa. — Donald Trump and Mike Pence dedicated an event Tuesday in suburban Philadelphia to doubling down on their call for the repeal and replacement of Obamacare, appearing with a coalition of elected Republicans with medical backgrounds to label the health care program a “catastrophe.”

The GOP presidential nominee vowed, if elected, to immediately “convene a special session” of Congress to strike down the Affordable Care Act.

“If we don’t repeal and replace Obamacare, we will destroy American health care forever,” Trump declared at a hotel ballroom near historic Valley Forge, focusing on the country’s health insurance challenges one week out from Election Day.

He and his running mate did not shed new light on their proposal for a replacement plan, but repeatedly denounced the current model created by President Barack Obama as what Pence called a “government takeover of health care.”

Federal officials said late last month that premiums in midlevel Obamacare plans will increase by an average of 25 percent.

Trump noted that the situation is worse in some states, citing a 116 percent jump expected next year in Arizona. He did not note that the majority of residents will qualify for subsidies.

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Former GOP presidential candidate Dr. Ben Carson, a neurosurgeon, also spoke against Obamacare at the private event as did members of the House’s “doc caucus,” including Rep. Tom Price (R-Georgia), an orthopedic surgeon, and Rep. Andy Harris (R-Maryland), an anesthesiologist.

Later, Trump stumped in Eau Claire, Wisconsin, a state that last voted for a GOP presidential nominee in 1984. Republican National Committee chairman Reince Priebus and Wisconsin Gov. Scott Walker, a former primary rival, were among the GOP officials who attended to support Trump.

The candidate urged those who had cast their ballots early for Clinton to act on their “buyers’ remorse” and change their votes.

In Pennsylvania, Trump followed his talk about health care by launching into his standard stump speech. He vowed to renew inner cities, return manufacturing jobs and cut middle-class taxes, but Pence targeted Obamacare almost entirely with his remarks.

“What good is a health care plan if you can’t afford to use it?” the Indiana governor asked in citing the rising premiums and deductibles amid stagnant wages. He said Obamacare has an “extraordinary record of economic failure” because it is a burden on family’s pocketbooks as well as business owners’ payrolls.

He said a Hillary Clinton presidency would be more of the same, referencing the renewed controversy that the Democrat faces over her private email server while secretary of state.

“We can’t trust Hillary Clinton with our health care anymore than we can trust her with classified information,” Pence said.

The Democratic nominee has pushed back against the GOP’s call for Obamacare’s repeal, acknowledging the high premiums and promising to “fix” it and make a “public option” available. The public option is a federally funded health care plan that would compete with private insurers.

The open-enrollment period for state and federal exchanges began Tuesday, marking Obamacare’s fourth year. The Department of Health and Human Services projected record enrollment.

Pence reiterated past Trump proposals to lower the cost of health insurance without growing the size of government.

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The campaign said it would use the “power of the free market” to steer pricing, get rid of the individual mandate, allow people to buy from plans across state lines and work with Congress to create health savings accounts.

A new tracking poll showed a very tight race between the nominees. Trump was leading by 1 point nationally in a four-way matchup while Clinton was up by 1 point in a head-to-head scenario, an ABC News/Washington Post poll showed.

Trump was scheduled to hold rallies this last full week of the campaign in what experts consider must-win states for him: Florida and North Carolina.