Key Republican senator just became the first major defection on the tax bill

Susan Walsh/AP

Sen. Ron Johnson

• Sen. Ron Johnson said he will not vote for the Senate's Tax Cuts and Jobs Act.
• Johnson said that he does not like the process being used to advance the bill - and the benefits for large corporations.
• This complicates the path forward for Senate GOP leaders, who already have little room for error.

Sen. Ron Johnson of Wisconsin on Wednesday became the first Republican member to publicly declare opposition to the Senate GOP tax bill.

Johnson told The Wall Street Journal's Siobhan Hughes that the bill, the Tax Cuts and Jobs Act, does not do enough to help small businesses while giving too much relief for large corporations.

"If they can pass it without me, let them," Johnson said. "I'm not going to vote for this tax package."

Republicans can afford only two defections. While GOP leaders are moving the bill through the budget reconciliation process, which only requires a simply majority vote in the Senate, Republicans control only 52 Senate seats.

Already, a handful of Republican senators have expressed misgivings about the legislation.

Moderates like Sen. Susan Collins have expressed concern over how much of the bill's benefits could go to wealthier Americans, as well as the bill's proposed repeal of the Affordable Care Act's individual mandate. Others like Sens. Jeff Flake and Bob Corker wavered over the huge amount of federal debt that would be added under the bill.

For Johnson, the biggest issue was the relative benefits for multinational corporations compared to pass-through entities, such as limited liability corporations and S-corporations.

Additionally, Johnson said that he did not like the process being used to pass the TCJA. The bill was released last Thursday after being kept under wraps. Recent changes have come rapidly.

"I don't like that process," Mr. Johnson told the Journal. "I find it pretty offensive, personally."