Democratic members of Oregon's congressional delegation, local officials, activists and thousands of residents held a rally Sunday to oppose Republican efforts to repeal the Affordable Care Act, also known as Obamacare.

U.S. Sens. Ron Wyden and Jeff Merkley were joined for the rally at a northeast Portland gymnasium by U.S. Reps. Earl Blumenauer, Suzanne Bonamici, Kurt Schrader and Portland Mayor Ted Wheeler.

"We're taking the gloves off," Wyden said, warning Republicans that a "titanic battle of a lifetime" would ensue over the health care law's future.

Wyden criticized Republican moves to repeal the law, which he characterized as "a Trojan horse" to give a tax break to the wealthy and put health care regulations in the hands of insurance companies.

"Not going to happen on our watch," he said.

Merkley praised the ACA for providing medical coverage to Americans with pre-existing conditions and for allowing additional numbers of poor people insurance under state Medicaid expansions.

"Should we allow an America where people have to struggle to stay alive until they can get on Medicare?" Merkley said.

Oregon's Medicaid expansion has insured an additional 300,000 people, bringing the total number on the program to more than 1.1 million -- or one in four Oregonians. Medicaid cost the state more than $13 billion during its last two-year budget.

Merkley said Republican criticism of the ACA is misplaced. Republicans -- even those in rural Oregon, he said -- favor individual aspects of the law, though they won't admit it.

Wheeler vowed "to fight tooth and nail" to protect the ACA against the Republican-lead Congress and President-elect Donald Trump, who he called "the most divisive president in U.S. history."

The ACA provided part of the funding that helped the city open hundreds of beds for the homeless during this month's record cold snap, Wheeler said. "That's at risk if we lose the ACA," he said.

The ACA is working rather well, Schrader said, despite criticism from conservative pundits like Glenn Beck and Bill O'Reilly, whom he called "naysayer hate mongers." Bonamici said repeal efforts are "heartless" and Blumenauer said health coverage should be expanded through a single-payer option or lowering eligibility requirements.

Many members of the crowd held signs indicating their support for Obamacare -- or that they themselves are insured by it.

Alexandra Ninneman, a first year medical student at Oregon Health and Science University, said the prospect of repealing the ACA is frightening. Her father is on Medicaid and she worries he'll lose coverage if the Affordable Care Act is repealed.

She has a message for Congress: "Protect Americans. Protect our patients."

The ACA isn't without its problems, said Richard Cohen, a veteran and retired businessman, but Republicans have yet to offer an alternative. "I'm not opposed to a better health insurance plan," he said. "Show me what it is."

Republicans in Congress have taken the first steps towards repealing the ACA, and given few specifics on what they would replace it with. The House and Senate passed a budget resolution last week directing lawmakers to draft repeal legislation. Votes were mainly along party lines.

Republicans lawmakers have sought to do away with the law almost continuously since it was enacted in 2010. They say it has driven up the cost of health care premiums or delivered bad coverage, among other criticisms.

Indeed, premiums have risen around the country as insurers abandon the health care exchanges. Oregon's effort to build its own exchange website, called Cover Oregon, was a boondoggle: The failed effort cost the state $300 million and enmeshed it in costly litigation.

Despite the ACA's shortcomings, Democratic leaders say it should be tweaked -- not repealed outright.

The ACA has reduced the federal deficit, Merkley said, because insurance provided under it gives Americans preventative health care. That cuts reliance on expensive emergency care, he said. Wyden said there are options for reducing health care costs that Congress has not considered, which he hopes to advocate for as the debate heats up.

Despite Democrats' best efforts to drum up support for keeping the ACA, there is a major stumbling block in their way: votes.

Republicans hold majorities in the House and Senate, and Trump has vowed to repeal the ACA.

Wyden and Merkley seemed undeterred.

Republicans are looking "increasingly skittish," Wyden said, because they don't yet have a plan for replacing the Affordable Care Act.

"We need a few Republicans to join us," Merkley said.

-- Gordon Friedman

gfriedman@oregonian.com; 503-221-8209