WASHINGTON — Barack Obama may not be running for anything these days, but his signature health care law was a big winner in Tuesday’s elections, as voters rebelled against Republican lawmakers who have blocked Obamacare’s Medicaid expansion.

Democrats are hopeful their victories are a harbinger of further gains as they look to capitalize on the law’s rising popularity in polls — and repeal legislation’s deep unpopularity — with more ballot initiatives, legislative efforts and campaign messages.

In Maine, voters passed a ballot initiative that would expand Medicaid to an estimated 70,000 residents by a margin of 18 points, 59-to-41, doing an end run around Gov. Paul LePage, a Republican who has vetoed five bills to do so.

LePage is already threatening to block the measure unless legislators can find a way to finance it without raising taxes, saying in a statement that “this fiscally irresponsible Medicaid expansion will be ruinous to Maine’s budget.”

Jonathan Schleifer, executive director of the Fairness Project, says the Maine initiative is only the start. His group, which helps coordinate progressive ballot initiatives around the country, is looking at putting expansion on the ballot in Utah and Idaho next year and potentially initiatives in Alaska to enshrine some Obamacare features into state law.

“We need to end the conversation around repealing Obamacare and make it very clear, as we did last night, that folks want to expand it,” Schleifer said. “We’re not waiting until 2020. We’re going to get as much of this done in 2018 as we can.”

The win in Maine came after months of failed attempts by President Donald Trump and Republicans in Congress to undo the Medicaid expansion nationally and cut the program further over time. It also comes as the Trump administration is exploring changes that could make Medicaid less accessible, like allowing states to impose work requirements.

Maine wasn’t the…