Nearly half of Americans disapprove of the sweeping tax proposal Republicans aim to pass in the coming days, according to a new poll.

Forty-seven percent of those surveyed said they disapprove of the similar bills passed by the House and Senate, the Monmouth University poll released Monday said. Only 26 percent of respondents said they approve, while 19 percent had no opinion and 8 percent wanted to wait to draw a conclusion until they saw a final bill.

For Republicans, the survey is just the latest in a string of dismal public opinion polls on the GOP tax plan. In a separate poll out Monday, the CNBC All-American Economic Survey found that 70 percent believe their taxes in the next couple of years will either stay the same or increase.

The GOP is barreling ahead, hoping to pass a joint bill out of the House and Senate this week to meet a year-end target. The poll was conducted before Friday's release of a final bill hashed out by the House and Senate.

A Gallup poll taken during the push for the 1986 tax reform bill showed that 39 percent of Americans approved of it, while 33 percent disapproved. The current GOP effort has partly fared worse in public opinion polling because Republicans are trying to pass it on a party line vote, said Patrick Murray, director of the Monmouth University Polling Institute.

Here are some of its other findings:

Among Republicans polled, 55 percent approve of the bill, while 16 percent disapprove. Seventy-two percent of Democrats oppose it and 7 percent back it. Only 20 percent of independents approve, while 53 percent disapprove.

Fifty percent believe their taxes will go up, 14 percent say their tax burden will fall and 25 percent think it will stay about the same. While millions of Americans are expected to see a tax increase — particularly after many individual cuts expire after 2025 — that pocket of American taxpayers is projected to be nowhere near half.

Seventeen percent called the GOP bill a "genuine attempt to reform the tax system." Thirty-five percent said Republicans wanted to approve it "mainly so they can claim a political victory." Another 35 percent believe "both reasons equally" are driving the GOP.

Fifty-three percent said the middle class has "not at all" benefited from President Donald Trump's policies. Twenty-five percent answered that the middle class has been helped "a little," while only 11 percent said it has benefited "a lot."

The poll of 806 adults, conducted from Dec. 10 to last Tuesday, has a margin of error of plus or minus 3.5 percentage points.

Republicans look to pass a plan by the end of the year partly to have a legislative victory to promote ahead of next year's midterm elections. They argue that the major tax cuts for businesses included in the bill would boost job creation and wage growth.

Democrats will likely seize on dismal public opinion polling on the plan and the fact that most individual tax cuts would expire under the plan while a corporate tax decrease would be permanent.