U.S. President Barack Obama had warned that a block of the Iran nuclear deal by U.S. lawmakers would accelerate Iran's path to a nuclear weapon. Pictured: Obama delivered remarks on a nuclear deal with Iran at American University in Washington, D.C., Aug. 5, 2015. Reuters

U.S. President Barack Obama now has the votes he needs to ensure that the highly controversial Iran nuclear agreement announced in July will make it past congressional road blocks. U.S. Sen. Barbara Mikulski, D-Md., announced Wednesday that she would support the deal, making her the 34th senator to do so. Her support means that even if the Senate as a whole is able to muster enough votes to overcome a filibuster, Obama's veto will be sustained.

"I have diligently worked to make an informed decision, one that weighs risk and considers a future 10, 15, 25 years from now," Mikulski said in a statement. "Without question, this vote is among the most serious I’ve taken. This vote has monumental and enduring consequences."

The deal provides the United Nations with the ability to inspect Iran's nuclear facilities in exchange for relaxed sanctions on Iran.