Congressional Republicans appear to be hurtling toward a showdown over Iran's access to the US dollar with little or no support from Democrats, potentially dooming their legislative efforts to block further concessions to Tehran.

House Foreign Affairs Committee Chairman Ed Royce, R-Calif., on April 19 unilaterally introduced legislation that would prohibit the Obama administration from allowing the US dollar to be used to facilitate trade transactions. Royce has so far failed to secure the endorsement of his Democratic colleague, Rep. Eliot Engel, D-N.Y., even as the Republican leadership's blessing suggests a House vote could come soon.

"We cannot grant Iran access to the US dollar in any form," House Majority Leader Kevin McCarthy, R-Calif., said in an April 19 press release endorsing the Royce bill. "Iran supports terrorism around the globe, continues to test ballistic missiles, and commits egregious human rights abuses against the Iranian people. Iran shouldn’t get relief simply because they agreed in word to a flawed nuclear deal. House Republicans are concerned with Iran’s destabilizing behavior and any potential access to the US dollar. I commend Chairman Royce for introducing this important legislation.”

And a spokesman for House Leader Paul Ryan, R-Wis., wrote a blog post April 18 endorsing Iran legislation using the same language as Royce.