WASHINGTON (Reuters) -A U.S. Senate bill that would require congressional approval for new tariffs gained more Republican support on Friday, in the second day of a stock market rout sparked by President Donald Trump's move to impose sweeping new taxes on imports. Republican U.S. Senators Lisa Murkowski of Alaska, Mitch McConnell of Kentucky, Jerry Moran of Kansas and Thom Tillis of North Carolina, joined on as co-sponsors of a bill introduced on Thursday by Republican Chuck Grassley of Iowa and Democrat Maria Cantwell of Washington that would terminate new tariffs within 60 days unless the U.S. Congress explicitly approves them.