WASHINGTON—Sen. Rand Paul (R., Ky.) said Wednesday that he would oppose the budget measure Republicans are counting on to begin the process of repealing the Affordable Care Act, leaving the effort in danger of derailing if any other GOP senators defect.

The Senate on Wednesday took its first procedural vote on the budget measure, a vehicle that Republicans can use to repeal the 2010 health-care law with a simple majority vote. Republicans now hold only 52 seats in the Senate, where most legislation needs 60 votes to pass.

Mr. Paul said Wednesday he would vote against the budget measure because it adds too much to the federal budget deficit for fiscal year 2017.

“I’m a no,” he said in a brief interview. “It adds $9.7 trillion in debt over 10 years.”

Other Senate Republicans, including Susan Collins of Maine and Lamar Alexander and Bob Corker of Tennessee, have voiced concerns about repealing the health-care law before the GOP has settled on a plan to replace it. However, all three voted to advance the budget in an early procedural vote Wednesday, which passed 51-48, allowing the Senate to consider the measure.

Mr. Paul was the only Republican to join the entire Democratic caucus in voting not to move forward with the budget blueprint. Sen. Dianne Feinstein (D., Calif.) didn’t vote.

Other senators could still raise objections ahead of the final vote—on either the plan to repeal the health-care law or on the budget itself.

Aware of the razor-thin margins, GOP Sens. Ted Cruz of Texas, Mike Lee of Utah and Marco Rubio of Florida wrote Tuesday in a joint letter to GOP Senate leaders that while they understood the budget was “primarily a mechanism to advance [the health law’s] repeal,” the Senate should still abstain from any budget devices that they oppose.

“Our votes in favor of the ‘Obamacare Repeal Resolution’ do not indicate in any way our support for the revenue, spending, and deficit numbers therein, nor for the use of those numbers as the basis for future federal budgets,” the three senators wrote, using the GOP nickname for the budget blueprint.

The next fiscal year’s budget, expected to pass this spring and help Republicans overhaul the tax code, must balance the federal budget in 10 years, they wrote.

Budget blueprints are nonbinding documents used by political parties to signal how they think federal dollars should be spent. The budget document introduced in the Senate Tuesday also starts the process of repealing the health-care law.

The Senate’s budget resolution directs four relevant committees, two in the Senate and two in the House, to write legislation by Jan. 27 that reconciles spending and tax policy with the budget blueprint for the coming fiscal year. Embedded in the committees’ legislation will be provisions that repeal much of the health law.

Democrats, who have paid a heavy political price for the health law’s unpopularity, said Republicans will now bear responsibility for any attempts to gut and replace it.

“Now, they’re gonna own it, and all the problems in the health-care system are going to be on their backs,” Senate Minority Leader Chuck Schumer (D., N.Y.) said Wednesday.

http://www.wsj.com/articles/rand-paul-endangers-health-law-repeal-1483557210