Senate Democrats have handed United States President Barack Obama a major foreign policy victory by blocking a Republican move to kill his landmark Iran nuclear deal, but it is still unclear how the deal will be implemented.
Under the accord struck between Iran and six world powers - the United States, Britain, France, Germany, Russia and China - Teheran would curtail its nuclear programme in exchange for relief from crippling economic sanctions.
"This vote is a victory for diplomacy, for American national security, and for the safety and security of the world," Mr Obama said in a statement after Thursday's vote.
But Republicans insisted that the fight would go on. Those opposing the deal have said it merely halts Iran's ability to develop nuclear weapons, does not provide for timely inspections and does nothing to stop Iran's support for militant groups such as Hamas.
House Speaker John Boehner said House Republicans will "use every tool at our disposal to stop, slow and delay this agreement from being fully implemented", including suing the President.
"That is an option that is very possible," Mr Boehner told reporters.
The 58-to-42 vote ensures that the resolution of disapproval of the Iran deal does not advance to the Senate floor for a yes or no vote.
But the Senate's Republican majority leader, Mr Mitch McConnell, wants another vote.
"We'll revisit the issue next week and see if maybe any folks want to change their minds," Mr McConnell said in a speech.
The resolution needed 60 votes to advance and Mr Obama has been spared from exercising his veto - a move that would have highlighted the ever-deepening rift between the Republican-led Congress and his administration.
Key questions still remain, including the issue of how inspections will be done and by whom, with some reports suggesting that Iranians themselves will be involved in the process.
These details are laid out in two side agreements between the International Atomic Energy Agency and Iran which have not been made public.
A law professor from the University of Utah, Dr Amos Guiora, said that moving forward, "there will have to be a process put in place... They are going to have to establish monitoring infrastructure".
He also questioned the "consequences of violation", including if and how the sanctions regime might be reimposed.
"It's those substantive questions that I really would hope would be addressed in the days and weeks ahead, because otherwise the agreement is useless," he said.
After the vote, major players also expressed their views on security issues in the region and the world.
Secretary of State John Kerry issued a statement saying that the administration would work with partners and allies in the region to "deepen our security cooperation, and to counter Iran's destabilising behaviour, including its support for terrorism".
Israeli Ambassador to the US Ron Dermer, who had lobbied dozens of lawmakers, said in a speech on Thursday night that he believes the deal "makes America and Israel much less safe".