On the 5th, the U.S. House of Representatives failed to pass a bill that sought to require President Trump to obtain congressional authorization before taking further military action against Iran. The previous day, the Senate had already rejected a similar bill.
The House vote was 212 in favor and 219 against, so the bill did not pass. The voting result was largely along party lines, with most Democrats supporting the bill and the vast majority of Republicans opposing it.
On the 4th, the Senate rejected a similar bill by a vote of 47 in favor and 53 against. Since Republicans hold a narrow majority in both the House and Senate, the results of the votes were not surprising.
According to the U.S. Constitution, only Congress can authorize the waging of war. A law passed by Congress in 1973 stipulates that only in cases of attacks against the United States or imminent threats causing a national emergency can the U.S. President undertake limited military action without congressional authorization.