Republicans must agree upon a companion budget plan if the tax effort is to get off the ground.
Mnuchin's outreach to the Senate on Tuesday would come after his muddled attempt last week to mollify outraged House conservatives over a deal Trump brokered with Democratic leaders to tie three-month extensions of government spending and the debt ceiling to hurricane relief funds.
The administration is cranking up a publicity campaign to build public support for the Republican president's tax goals, and Trump was due to meet with three Democratic senators Tuesday to discuss taxes.
The new law did lots of important things, such as shifting a significant part of the tax burden from individuals to corporations.
Tonight, the president will be wining and dining a bipartisan group at the White House on the issue.
Manchin says he does not expect the plan would target popular tax deductions for mortgage interest and charitable giving.
Trump's new friends Chuck and Nancy may not be much help here, although it's easier to wheel and deal when you're giving money away.
Senate Republican leader Mitch McConnell voiced doubt on Tuesday that the US debt ceiling would be eliminated permanently, an idea floated by Democrats and embraced by Republican President Donald Trump last week.
If he was serious about reform, Trump wouldn't have attacked Missouri Sen.
The other two were Joe Donnelly of IN and Heidi Heitkamp of North Dakota, who were also at Tuesday's dinner and, like Manchin, are considered moderate Democrats. John Thune of South Dakota, Orrin Hatch of Utah and Pat Toomey of Pennsylvania.
"What I want to focus on is doing what's right by the American people to create jobs, growing the economy, to make sure we're focused on tax reform", Gardner said.
Trump is reportedly set to launch into a prolonged cross country tour to advocate for the cuts.
But the Big Six have yet to finalize an agreement, and lobbyists say the group is still undecided on basic elements of a tax reform plan, including whether tax legislation should add to the federal deficit or be revenue-neutral.
The deal for aid to Hurricane Harvey victims, which included a short-term lifting of the debt ceiling and stopgap funding for government operations through December 8, was a bitter pill to swallow for many House conservatives, who had pushed to attach spending cuts to any increase in the government's federal borrowing limit.