President Trump is optimistic Senate Republicans will approve a resolution Thursday that will serve as a vehicle for his administration's tax reform proposal.

"Republicans are going for the big Budget approval today, first step toward massive tax cuts. I think we have the votes, but who knows?" Trump tweeted Thursday morning.

The Senate is expected to vote on and approve a 2018 budget as early as today, and the House could take it up when it returns next week. Passing the budget will allow passage of a tax reform bill that can be advanced in the Senate with just a simple majority vote, instead of the usual 60 votes.

The Trump White House has proposed the most aggressive tax reforms in decades. House Speaker Paul Ryan recently said he will keep Congress in session through Christmas if it means getting the bill to the president's desk.

In late September, the Senate Budget Committee set a Nov. 13 deadline for committees to draft tax reform bills.