Differences between the Missouri House and Senate may once again kill an effort to nullify federal gun laws.

The Missouri House voted Tuesday evening by a veto-proof margin, 109-42, to approve a conference committee’s proposed final version of the bill, officially known as the “Second Amendment Preservation Act.”

But the chief Senate sponsor, state Sen. Brian Nieves, R-Washington, declined to sign the panel’s compromise and told reporters that he may not bring up the version for a final Senate vote before this session ends on Friday. The result would be to kill the bill.

The conference committee had accepted the position of the chief House sponsor, Rep. Doug Funderburk, R-St. Charles, that the gun bill shouldn’t penalize federal law enforcement officers who tried to enforce federal laws that some pro-gun advocates believe infringe on their constitutional rights. Nieves’ Senate bill had included some penalties and he objected at removing all of them.

Nieves had come close last year in winning passage of a stricter gun nullification bill, which passed the House but was killed by Senate GOP leaders, largely because of law-enforcement groups’ objections to some of the 2013 provisions. Those earlier provisions included the proposed penalties against federal authorities who attempted to enforce federal gun laws.

Funderburk emphasized that he had made a commitment to law-enforcement groups to not include any such penalties in this year’s version.