Story highlights Republicans are worried what it means to have few legislative wins by August recess

Strategists say the party hasn't done enough with its majorities to keep voters engaged

Ten Democrats in states Trump won in 2016 up for re-election in 2018

Washington (CNN) Sen. Dean Heller has carefully avoided endorsing a politically unpopular Republican health care bill.

But, with the two sitting next to each other at a White House lunch Wednesday, President Donald Trump suggested Heller would face much graver consequences if he opposes a last-ditch effort to pass that bill. Doing so, Trump said, would amount to "telling America that you're fine with Obamacare."

"Look, he wants to remain a senator, doesn't he?" Trump said of Heller.

The Nevada senator is among the most endangered Republicans headed into the 2018 midterm elections. And Trump's comment was an acknowledgment of the peril facing the GOP if it fails to deliver on its seven-year promise of repealing former President Barack Obama's Affordable Care Act.

Already facing an energized Democratic opposition, Republicans are now confronting the prospect of a deeply disappointed conservative base that has watched the party fall short on health care despite controlling the House, Senate and presidency.

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