WASHINGTON — As more than 40 subdued Republican senators lunched on Chick-fil-A at a closed-door session last week, Senator Cory Gardner of Colorado painted a dire picture for his colleagues. Campaign fund-raising was drying up, he said, because of widespread disappointment among donors over the inability of the Republican Senate to repeal the Affordable Care Act or do much of anything else.
Mr. Gardner is in charge of his party’s midterm re-election push, and he warned that donors of all stripes were refusing to contribute another penny until the struggling majority produced some concrete results.
“Donors are furious,” one person knowledgeable about the private meeting quoted Mr. Gardner as saying. “We haven’t kept our promise.”
The backlash from big donors as well as the grass roots panicked Senate Republicans and was part of the motivation behind the sudden zeal to take one last crack at repealing the health care law before the end of the month. That effort faltered Friday with new opposition from Senator John McCain of Arizona, the perennial maverick who had scuttled the Senate’s first repeal effort. Now Republicans must confront the possibility that they will once again let down their backers with no big win in sight.
The latest unsightly pileup over health care was exactly what some Republicans had wanted to avoid by abandoning the repeal effort and skipping straight to tax cuts after the previous embarrassing health care collapse about eight weeks ago. Instead, Senate Republicans got caught up in a rushed, last-ditch repeal attempt that not only seems unlikely to prevail, but will only serve to remind disillusioned donors about the party’s governing difficulties.
This was not what Republicans had envisioned. Preparing for the 2018 midterm elections, they had thought they were in a strong position to maintain or expand their majority. Democrats must defend 25 seats — including 10 in states won last year by President Trump — while just eight Republican-held seats will be on the ballot. But their governing struggles — and attacks on congressional leaders by Mr. Trump — have soured their base, leaving the Senate majority feeling desperate.
Addressing his anxious colleagues at their weekly meeting on Sept. 12, Mr. Gardner had a simple message: If we don’t have something to run on, we are going to squander this opportunity.
Republican senators strive to keep discussions at their weekly luncheons secret to allow for candid discussions. This meeting was held off the Capitol grounds, at the headquarters of the National Republican Senatorial Committee, to enable a broad discussion of politics. Neither lawmakers nor staff would go on the record to discuss it, but the session was described by multiple people knowledgeable about what occurred.
They said Mr. Gardner did not specifically urge approval of the so-called Graham-Cassidy health proposal that Republicans were considering bringing to the Senate floor next week. He was seen as speaking more generally and mainly looking forward to the coming debate over tax cuts.
But the fund-raising drought has become a growing worry and lawmakers have not been reticent about noting that their political fate could be tied to the outcome on health care and how Senate Republicans handle other issues ahead.
Senator Charles E. Grassley of Iowa, who has been deeply involved in health policy for years, told reporters back home that he could count 10 reasons the new health proposal should not reach the floor, but that Republicans needed to press ahead regardless in order to fulfill their longstanding promise to replace and repeal President Barack Obama’s Affordable Care Act.
“Republicans campaigned on this so often that we have a responsibility to carry out what you said in the campaign,” Grassley said in a conference call with Iowa reporters. “That’s pretty much as much of a reason as the substance of the bill.”
Senator Pat Roberts of Kansas was even more blunt in a conversation with Vox. “If we do nothing, it has a tremendous impact on the 2018 elections, and whether or not Republicans still maintain control and we have the gavel,” he said.
Republicans say the fund-raising drop-off has been steep and across the board, from big donations to the small ones the party solicits online from the grass roots. They say the hostile views of both large and small donors are in unusual alignment and that the negative sentiment is crystallized in the fund-raising decline.
One party official noted that Senate Republicans had a lucrative March, raising $7 million — an off-year record for the organization. But in the aftermath of the failed health repeal effort before the August recess and other setbacks, the take dropped to $2 million in July and August — a poor showing for a majority party with a decided advantage on the midterm map.
The totals have left Republicans increasingly worried about having the funds they need next year. Mr. Gardner told his colleagues that a major Colorado contributor who played a role in his own campaign says party donors are reluctant to give any more money until congressional Republicans demonstrate results.
Party operatives say it is hard to assess the full impact of Mr. Trump’s summer attacks on Senator Mitch McConnell of Kentucky, the majority leader, as well as the president’s frustration at the inability of the Republican-led Congress to repeal the health care law. But they assume his criticism has been a factor in driving down support.
Senate Republicans are entering a pivotal week. They have been scrambling to find the votes for the contentious new repeal effort before the Sept. 30 expiration of special budget authority, which would allow the bill to pass with a simple majority and not 60 votes. But Mr. McCain’s decision to join at least two other Republicans — Senators Susan Collins of Maine and Rand Paul of Kentucky — in finding fault with the measure put its fate in real peril.
If the bill is short of votes, Mr. McConnell could choose not to bring it to the floor at all to prevent a second embarrassing defeat on health care and spare Republicans a difficult vote.
Mr. McConnell faces other immediate challenges as well. A primary on Tuesday in Alabama pits his candidate, Senator Luther Strange, against Roy Moore, a former chief justice of the state Supreme Court challenging him as an outsider. The defeat of Mr. Strange would further rattle his colleagues and be seen as a major rebuke to Mr. McConnell and the Republican establishment in Washington for their failure to deliver on health care repeal and other issues.
Republicans are also set to roll out their income tax overhaul plan next week in an effort to build support for it and find something the party can deliver to the president’s desk. They see the tax plan as their best opportunity to win back the allegiance of donors.
With health care repeal teetering yet again, the one thing they know for sure is that they need to show some accomplishments, and they need to do so fast.