Protesters block a street during a demonstration against the Republican bill in the U.S. Senate to replace former President Barack Obama's health care law, in Salt Lake City, June 27, 2017. Credit: Rick Bowmer | AP

WASHINGTON — Hundreds of thousands of poor Americans look poised to gain health coverage across the country, as Democrats made gains in key state elections Tuesday and voters in several Western states appeared likely to back measures to expand Medicaid.

At least four — and perhaps more — states now look on track to join the 33 that have already chosen to expand Medicaid eligibility through the Affordable Care Act, often called Obamacare.

Election results Tuesday night also underscored the powerful force that health care — the 2010 health law in particular — has been in this year’s political campaigns. Democrats campaigning on the issue took control of the House of Representatives and effectively foreclosed any new Republican effort to roll back the law in Congress.

Despite last-minute efforts by President Donald Trump and GOP candidates to claim they would protect Americans with pre-existing conditions, Democrats relentlessly hammered Republicans during the campaign for their repeated efforts to repeal the law, including its protections for sick Americans.

The most immediate coverage gains look likely to occur in Nebraska, Idaho and Utah, where ballot measures to expand Medicaid were comfortably ahead.

But Medicaid expansion may also be on the way in Kansas, where Democrat Laura Kelly defeated a conservative Republican in the race for governor. The state’s GOP-controlled state Legislature had tried to expand the safety-net program under pressure from financially struggling hospitals in the state, but the expansion was blocked by former Republican Gov. Sam Brownback.

A victory in Maine by Democratic gubernatorial candidate Janet Mills should clear the way for that state to finally expand Medicaid coverage as well.

Maine voters approved an expansion measure last year, but Gov. Paul LePage, a Republican, has refused to implement it.

Results in a fourth Medicaid ballot measure — to extend a Medicaid expansion in Montana that is slated to sunset in 2019 — were also expected later Tuesday night. The race there has been close, with the tobacco industry spending heavily to defeat the measure because the expansion will be partially financed with tobacco tax revenues.

In Wisconsin, another state where election results could dictate the future of Medicaid coverage, the gubernatorial race remained very tight late Tuesday night, as incumbent Republican Gov. Scott Walker, a leading foe of the health care law, was knotted with Democratic challenger Tony Evers.

Across the country this year, Democrats made defending the health care law a centerpiece of their campaigns up and down the ticket.

The strategy was not successful everywhere. In Florida, Democrat Andrew Gillum fell short of his bid to replace outgoing Republican Gov. Rick Scott, who has fought Medicaid expansion for years. That will likely leave hundreds of thousands of low-income Floridians without access to health coverage.

But Democratic victories — along with support of Medicaid measures in deeply red states — represented a powerful repudiation of the long Republican campaign to repeal the health care law and roll back its protections for people with pre-existing medical conditions.

Medicaid, the half-century-old government health plan for the poor, is a pillar of the health care law’s program for guaranteeing coverage and has helped drive a historic drop in the nation’s uninsured rate.

The law makes hundreds of billions of federal dollars available to states to extend Medicaid coverage to poor adults, a population that had been largely excluded. Medicaid eligibility historically was limited to vulnerable populations, such as low-income children, pregnant women, the elderly and people with disabilities.

Most states moved to expand eligibility as soon as the health care law made additional federal aid available. To date, 33 states and the District of Columbia have elected to expand.

GOP opposition — concentrated in the Deep South and the Great Plains — has left about 2.2 million low-income Americans without insurance protections in the states that haven’t expanded Medicaid, according to an analysis by the nonprofit Kaiser Family Foundation. Almost half of those uninsured people live in just two states, Florida and Texas.

Many Republicans have argued that the program is unaffordable and ineffective, though a growing body of research shows Medicaid significantly improves poor Americans’ access to vital medical care.

And the Trump administration continues to advocate hundreds of billions of dollars in cuts in federal health care funding for states that, if ever enacted, would force massive cuts in health coverage for poor Americans.