WASHINGTON (AP) ― A bill that would levy tough new sanctions on Iran if it fails to sign an agreement to curb its nuclear program cleared a Senate committee on Thursday. But lawmakers are holding off on a full Senate vote to see whether diplomatic negotiations yield a deal.

Republican and Democratic members of the Senate Banking, Housing and Urban Affairs Committee voted 18-4 to pass the bill aimed at ramping up economic pressure on Iran starting in July if it doesn’t ink an international deal preventing it from having the capability to develop a nuclear weapon.

Republicans still can move ahead, but that’s unlikely without Democratic support. They wouldn’t have enough votes to override President Barack Obama, who says he’ll veto the legislation because it would derail the diplomatic effort to reach a deal.

The U.S. and other nations negotiating with Tehran have long suspected Iran’s nuclear program is secretly aimed at atomic weapons capability. Tehran insists the program is entirely devoted to civilian purposes.

Talks with Tehran have been extended until July, with the goal of reaching a framework for a deal by the end of March. Iran’s state-run IRNA news service said Wednesday that Iranian lawmakers have proposed a bill that would scuttle the diplomatic effort if the U.S. imposed new U.S. sanctions.

A movement to levy more sanctions to cripple the Iranian economy had been moving fast on Capitol Hill. But on Tuesday, Sen. Bob Menendez, who coauthored the measure with Sen. Mark Kirk and nine other Democrats, told Obama in a letter that they wouldn’t push the bill at least until the end of March.

“While I will move to vote today in support of the underlying legislation, I have no intention of moving forward and supporting it on the floor if it is brought before the March 24 deadline” when lawmakers will be able to ascertain “whether or not an agreement is possible and what that agreement would look like,” Menendez said.