Rand Paul announced Monday that he plans to vote for the Senate version of the tax cut legislation, providing a boost to GOP leaders hoping to advance the bill through the upper chamber this week.

"I plan to vote for this bill as it stands right now," the Kentucky Republican wrote in an op-ed published on Fox News, explaining that the tax cut isn't as big as he had hoped, but that the bill has improved as it has been written.

Senate Majority Leader Mitch McConnell can lose only two Republican votes and still pass tax reform without Democratic help. Previously, Paul's vote had been in question as he had criticized the GOP approach and voted against the budget resolution that unlocked the process that would allow the bill to pass the Senate with a simple majority.

A handful of other Republican senators have expressed hesitance about the bill. One, Ron Johnson of Wisconsin, has said he is against it but that he is working with leaders and the Trump administration to change the legislation.

Republicans are expected to amend the bill to get buy-in from cautious party members.

One key to winning over Paul was including repeal of the Obamacare individual mandate in the bill.

Paul wrote Monday that he would have preferred bigger tax cuts for individuals, and for the individual tax changes to be permanent rather than temporary as they are written to be in the current legislation.

He added that some of the shortcomings of the bill could be fixed in future legislation.

"The good news is — we can do this every year," he wrote. "Want a bigger tax cut? Urge your legislators to do one every single year. I’ll sponsor it. Want them to be permanent? Well, one good start is to keep extending them, every single year."