Trump courting Democrats on tax reform A group of six senators will be dining tonight with President Trump.

 -- A group of six senators is expected to dine tonight with President Trump at the White House in what's being touted as a "bipartisan working dinner" to address tax reform, multiple Congressional aides have confirmed to ABC News.

The Democrats expected to attend will be Sens. Joe Manchin (W. Virginia), Joe Donnelly (Indiana) and Heidi Heitkamp (North Dakota) and the Republicans are Sens. Orrin Hatch (Utah), Pat Toomey (Pennsylvania) and John Thune (South Dakota).

The dinner comes as the White House and Congressional lawmakers continue to push along the slow-moving debate on tax reform. Trump over the weekend said he wanted to "speed up" the process, but lawmakers insist it's going to take a lot of time and effort to get something passed before the end of the year.

The three moderate Democrats each hail from red states, and are all up for re-election next year. The dinner could be seen as a boost to their campaigns, as Trump easily won in their states last year.

Donnelly, Heitkamp, and Manchin are also more likely to lend their support to a GOP tax package that includes widespread cuts and reforms because they are vulnerable heading into a risky midterm election.

Notably, the senators were the only three Democrats who did not sign a letter addressed to leadership that said the Democratic caucus would not support a tax overhaul that cuts taxes for the "top 1 percent" or adds to the government's $20 trillion debt.

The three Republicans who are attending all sit on the Senate Finance Committee, which is leading the charge on tax reform. The House and Senate are set to begin holding hearings on the details of their tax plan, Thune said on Monday.

The as-yet undrafted bill to overhaul the tax code remains a "top priority" for Republicans.

"I'm not making any predictions about it being done by the end of the year, but that's the hope, the aspiration and the plan," Thune said.

Democrats have been firing warning shots to their Republican colleagues for potentially drafting another bill in secret and out of the public's view.

"It’s middle class Americans, not those in the 1%, who deserve tax relief. So we Democrats will not go along with a tax plan that includes a tax cut for those who need it least," Senate Minority Leader Chuck Schumer said today during a conference call with reporters.

The White House released its own statement this afternoon: "The President is committed to getting tax relief for middle class Americans passed and is willing to work with Democrats and Republicans to do it."