Sen. Susan Collins will be casting a deciding "yes" vote alongside her Republican colleagues to overhaul the tax code, she announced Friday.

“Having secured ... key improvements in the bill, as well as the commitments to legislation to help lower health insurance premiums, I will cast my vote in support of the Senate tax reform bill," she said. "As revised, this bill will provide much-needed tax relief and simplification for lower- and middle-income families, while spurring the creation of good jobs and greater economic growth.”

The bill, the Tax Cuts and Jobs Act, would nearly double the standard deduction and expand the child tax credit. The support of Collins, a centrist from Maine, means that the bill will pass the Senate with at least 51 votes. Because the Senate is advancing the bill through a budget measure known as reconciliation, and all Democrats are expected to vote against the legislation, the party needs at least 50 votes to guarantee passage, assuming a tie-breaking vote by Vice President Mike Pence.

“I don’t think there is a single American who thinks that our current tax code is fair, simple, or promotes economic growth," Collins said. "We need a tax system that will boost the economy, help the middle class, and encourage small businesses to grow and create jobs. If we stimulate the economy through tax reform, we can significantly increase federal revenues while boosting Americans’ take-home pay."

Collins detailed in her statement how the caucus was able to gain her support. Four amendments Collins introduced were added to the tax bill. One would allow taxpayers to deduct up to $10,000 in state and local property taxes, and another would increase the medical expense deduction.

Collins also said she secured promises on Medicare, the healthcare program for seniors. She had been concerned about $25 billion in automatic cuts to Medicare projected by the Congressional Budget Office that would be triggered for fiscal 2018 as a result of a bill passed in 2010 called the Pay-As-You-Go Act.

“I wrote to the majority leader urging that we immediately remove the threat of an automatic cut in the program’s funding, which has been done on numerous occasions before, and I am pleased that he has said these cuts will be avoided," she said.

House Speaker Paul Ryan, R-Wis., also made the same pledge, she noted.

Collins, who helped sink a healthcare bill this summer called "skinny repeal," plans to vote in favor of the tax bill, the Tax Cuts and Jobs Act even though it contains a similar provision that would repeal the individual mandate penalties under Obamacare.

“The skinny repeal bill had many other provisions in it,” Collins told reporters Thursday. “It repealed the employer mandate, eliminated funding for Planned Parenthood and had many other provisions and so it is not comparable at all [to mandate repeal]."

Collins said in her statement about her decision that she had been "deeply concerned" about repealing the individual mandate penalties, but went on to detail that she had negotiated other measures on Obamacare that she said she expected would help lower premiums.

Senate leadership was able to secure her support because they agreed to take up a two-year, $5 billion-a-year reinsurance bill she introduced with Sen. Bill Nelson, D-Fla. Leaders also vowed to take up a bipartisan healthcare package known as Alexander-Murray that would make Obamacare insurer payments for two years in exchange for more flexibility for states to waive Obamacare regulations.

The timing and vehicle for these bills is still being worked out, but one possible avenue would be through a continuing resolution. Senate Minority Leader Chuck Schumer has said that Democrats would back out of supporting Alexander-Murray if Republicans pass the tax bill, but others, including Sen. Patty Murray, D-Wash., who helped negotiate the package, haven't made similar commitments.

After the tax bill passes, it will head to conference with the House, where it may face additional changes. The House version of the bill did not contain repeal of the individual mandate penalties.

Sen. Bob Corker, R-Tenn., has not announced whether he plans to support the bill.