John McCain says he will support the GOP tax bill, giving the plan an enormous boost

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U.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.

• Sen. John McCain said he would vote for the Republican tax plan on Thursday.
• McCain said that the bill is "far from perfect" but the bill 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 Republican tax plan, helping to bolster the chances of the plan as it heads towards 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."

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 bills' impact on the national debt during those debates. According to the Joint Committee on Taxation, the current bill would add roughly $1.5 trillion to the deficit over the next 10 years.

Additionally, McCain's vote to block the Obamacare repeal bills over the summer added a degree of uncertainty to his support. During that debate, McCain gave an impassioned speech in support of regular order in the Senate instead of the rushed process used to bring the healthcare bills to the floor.

According to McCain's statement, the hearings the tax bill - named the tax Cuts and Jobs Act TCJA) - were enough to appease 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/. A number of other GOP members are holding out their support from the bill due to concerns over the debt, the bill's treatment of pass-through businesses, or the healthcare changes in the bill.