john mccain chuck schumerU.S. Sen. John McCain (R-AZ) (L) and U.S. Sen. Charles Schumer (D-NY) share a moment as they speak to members of the press outside the Senate Chamber June 27, 2013 at the U.S. Capitol in Washington, DC. Alex Wong/Getty Images

  • Sen. John McCain said Thursday that he would vote for the Republican tax plan.
  • McCain said that the bill is “far from perfect” but that it would help the US economy.
  • McCain’s support was in question due to his opposition to the Bush tax cuts, concerns over the national debt, and votes against the GOP Obamacare repeal bills.

Sen. John McCain announced Thursday that he will support the Senate Republican tax plan, significantly boosting the legislation’s chances as it speeds toward a vote.

“After careful thought and consideration, I have decided to support the Senate tax reform bill,” McCain said in a statement. “I believe this legislation, though far from perfect, would enhance American competitiveness, boost the economy, and provide long overdue tax relief for middle class families.”

Stocks surged amid Thursday’s tax reform developments. The Dow jumped over 350 points, while the Nasdaq jumped more than 60.

McCain’s support was considered a toss-up due to his votes against tax cuts under President George W. Bush in 2001 and 2003. The Arizona senator cited concerns over the bill’s potential impact on the national debt during those debates and had expressed similar qualms this time. According to the Joint Committee on Taxation, the Senate bill would add roughly $1.5 trillion to the deficit over the next 10 years.

McCain was also considered a question mark because of his votes to block the Obamacare repeal bills over the summer. During that debate, McCain gave an impassioned speech in support of regular order in the Senate instead of the rushed process Republican leaders used to bring the healthcare bills to the floor.

McCain said in his statement that hearings the tax bill – the tax Cuts and Jobs Act TCJA) — were enough to please him.

“For months, I have called for a return to regular order, and I am pleased that this important bill was considered through the normal legislative processes, with several hearings and a thorough mark-up in the Senate Finance Committee during which more than 350 amendments were filed and 69 received a vote,” McCain said.

The Senate is currently debating the TCJA and is expected to hold a vote on the bill late Thursday night or Friday. Several other GOP members are holding out support from the bill due to concerns over the deficit and debt, the bill’s treatment of pass-through businesses, or proposed healthcare changes in the bill.