WASHINGTON (AP) — Fifty-nine senators now back a new sanctions package they say would increase the pressure on Iran to make nuclear concessions, according to congressional aides. The count brings Congress closer to passing a bill the Obama administration considers a threat to a historic diplomatic opportunity.

The senators in favor include every Republican except Jeff Flake of Arizona and Rand Paul of Kentucky, aides said. Sixteen Democrats are on board including Sen. Chuck Schumer of New York, a top ally of President Barack Obama. Many more are understood to be sitting on the fence.