The Senate on Wednesday rejected the seventh attempt by Democrats to force an end to American involvement in the war on Iran, even as the ranks of Republicans opposed to Donald Trump’s strategy grew. The war powers resolution proposed by Jeff Merkley, a Democratic senator of Oregon, failed in a 49-50 vote. All Democrats with the exception of John Fetterman of Pennsylvania supported its advancement. Since the conflict began in February, Democrats have repeatedly offered such resolutions, without success. But for the first time on Wednesday, Alaska’s Lisa Murkowski voted in favor, joining fellow Republicans Rand Paul of Kentucky and Susan Collins of Maine. All other Republicans in attendance voted against it. A spokesperson for Murkowski did not immediately respond to a request for comment.…