Protesters demonstrate near the full Senate budget committee markup of the tax reform legislation on Capital Hill November 28, 2017 in Washington, DC.

Opposition has grown among Americans to a Republican tax plan before the U.S. Congress, with 49 percent of people who were aware of the measure saying they opposed it, up from 41 percent in October, according to a Reuters/Ipsos poll released on Wednesday.

Congressional Republicans are trying to rush their tax legislation to a vote on the Senate floor before the end of the week. President Donald Trump strongly backs the bill and wants to sign it into law before the end of the year.

In addition to the 49 percent who said they opposed the Republican tax bill, 29 percent said they supported it and 22 percent said they "don't know," according to the Reuters/Ipsos opinion poll of 1,257 adults conducted from Thursday to Monday.

When asked "who stands to benefit most" from the plan, more than half of all American adults surveyed selected either the wealthy or large U.S. corporations. Fourteen percent chose "all Americans," 6 percent picked the middle class, and 2 percent chose lower-income Americans.

The tax bill being crafted in the Senate would slash the corporate tax rate, eliminate some taxes paid only by rich Americans and offer a mixed bag or temporary tax cuts for other individuals and families.

As congressional discussion on the bill has unfolded, public opposition to it has risen, on average, following Trump's unveiling of a nine-page "framework" on Sept. 27 that started the debate in earnest, Reuters/Ipsos polling showed.

On Oct. 24, for example, among adults who said they had heard of the "tax reform plan recently proposed by congressional Republicans," 41 percent said they opposed it, while 31 percent said they "don't know" and just 28 percent said they supported it.

Trump and his fellow Republicans are determined to make a tax code overhaul their first major legislative win since taking control of the White House and Congress in January.

The House of Representatives on Nov. 16 approved its own tax bill. The Senate is expected to decide on Wednesday whether to begin debating its proposal, as the measure moves toward a decisive floor vote later this week.

The two chambers would need to reconcile differences between their plans before legislation could be sent to the White House for Trump's signature.

In the Nov. 23-27 poll, 59 percent of Republicans supported the tax bill, 26 percent said they did not know and 15 percent opposed it. Among Democrats, 82 percent opposed it, 11 percent said they did not know and 8 percent supported it.

The online poll has a credibility interval, a measure of accuracy, of 3 percentage points.