Senate Republicans will attempt to pass a bill that would bar abortions after the fifth month of a pregnancy, with Sen. Lindsey Graham as the lead sponsor, the Washington Examiner has learned.

The South Carolina Republican's bill is a companion to the House-passed Pain Capable Unborn Child Protection Act. "Science tells us that unborn babies can feel touch as soon as eight weeks into the pregnancy; they feel pain at 20 weeks," Rep. Marsha Blackburn, R-Tenn., said on the House floor while leading the debate on the bill, arguing also that the bill would be "an appropriate response to the Kermit Gosnell house of horrors."

Republican aides in both chambers of Congress confirmed that Graham is the lead sponsor. He is expected to introduce the bill next week.

The proposed legislation was the subject of more debate in such a pro-life Republican conference than you might expect. Some lawmakers, such as Sen. Mike Lee, R-Utah, have concerns about the constitutionality of invoking Congress's authority to regulate commerce as the basis for the legislation. (That's the same constitutional provision that President Obama's attorneys invoked to defend Obamacare's individual mandate. Lee and the attorneys challenging the law argued that the Commerce Clause was being construed far too broadly.)

In 2003, the Supreme Court upheld a partial-birth abortion ban rooted in the Commerce Clause, but Justice Clarence Thomas and Justice Antonin Scalia emphasized in a concurring opinion that "the court's abortion jurisprudence ... has no basis in the Constitution." The concurrence also noted that "whether the Act constitutes a permissible exercise of Congress' power under the Commerce Clause is not before the Court."

By leading the push for the late-term abortion ban, Graham may strengthen his effort to hold off his challengers in the conservative state's Republican primary. Graham currently leads the field with 51 percent support, according to a new survey from Harper Polling/ConservativeIntel, but he remains vulnerable.

"Only 37 percent of likely voters view him favorably, whereas 44 percent view him unfavorably," Conservative Intel's David Freddoso wrote Wednesday.

That said, the bill is no election-year conversion for Graham. Although he's better-known as a foreign policy leader in the Senate, Graham introduced the Unborn Victims of Violence Act in 1999, when he was still a member of the House of Representatives.