WASHINGTON (TNS) — Republicans are investing enormous amounts of political capital and dollars to pump up support for their tax bill in a risky, last-ditch legislative undertaking ahead of next year's midterm elections.

A group aligned with House Speaker Paul D. Ryan, R-Wis., has spent $20 million so far on ads and outreach in communities across the nation. Senate Majority Leader Mitch McConnell, R-Ky., is set to fast-track the bill through the chamber next week.

The problem is, voters just don't seem to be that interested.

Polls show most Americans view the tax bill as benefiting the wealthy and corporations, skeptical that it would do much for middle-class taxpayers. Outside analyses of the bill echo those assessments despite revisions.

Republicans are nevertheless rushing ahead on a plan that may please wealthy donors, but it is opposed by most major categories of voters, including independents, women, minorities and young people, according to a recent Quinnipiac University poll. Even among Republicans, support is hardly overwhelming, with 60 percent approving the plan, 15 percent disapproving and 26 percent unsure.

Such lackluster enthusiasm and Republicans' failure so far to sell their tax plan to middle-class Americans raises questions about whether the issue will be the slam-dunk in the 2018 midterm elections that party leaders predict. After the failure to repeal the Affordable Care Act, Republicans are desperate for a political win.

"I don't see any political reward in passing or not passing tax reform legislation," said David Wasserman, who analyzes House races for the nonpartisan Cook Political Report. "I don't think the Trump base of the Republican Party sees this as an issue that would suddenly cause them to run to the polls."

Part of the problem has been the unusual speed by which Republicans are muscling through the House and Senate tax bills, which would cut corporate rates to their lowest level in decades, 20 percent, but make only temporary cuts to individual taxes while doing away with popular write-offs and deductions.

Republicans have been unable to build public momentum without the prolonged hearings and debates that would be normal for legislation of this magnitude.

But party donors have lost patience with the lack of legislative accomplishments, telling lawmakers not to bother calling and asking for campaign checks for the midterm elections until they have something to show for their hold on Congress and the White House.

"From the very start, we said that failure is not an option," Ryan said last week after House Republicans passed their version of the Tax Cuts and Jobs Act.

Perhaps more than any other Republican, Ryan has taken it upon himself to build support for the tax plan. The Ryan-aligned American Action Network has spent $20 million since August on television and radio ads and other tools to try to bolster lawmakers, shore up voter support for the tax bill and help shape public opinion in more than 50 House districts.

Democrats have launched no comparable effort against the tax bill, even though House Minority Leader Nancy Pelosi, D-Calif., is a fundraising powerhouse whose haul is expected to meet if not surpass Ryan's effort, despite being in the minority party.

Instead, Democrats are relying on the content of the tax bill itself to turn away voters.

"We don't need to match them dollar for dollar because they're pushing bad policy that hurts the middle class," said Charlie Kelly, executive director of the Pelosi-aligned House Majority PAC. "The reality is no amount of money can dress this up and make it look good," he said.

Voter attitudes may certainly shift over time, as happened with the Affordable Care Act, which rarely polled well among voters while Barack Obama was president and became popular only when it was seriously threatened with repeal by President Donald Trump and Republicans.

A similar road may be ahead for the tax bill. Republicans set many of the bill's effective dates — including the new individual tax rates and end of various itemized deductions — for the 2019 tax year, which means taxpayers may not begin to fully feel the effect until well after the midterm elections.