WASHINGTON, July 9 (Reuters) - Nearly 20 U.S. senators now back legislation to help protect Afghan civilians who supported U.S. forces during the 20-year-long war in their country, a lead sponsor of the bill said on Friday, a day after President Joe Biden set a target date of Aug. 31 for withdrawal. Democratic U.S. Senator Jeanne Shaheen said at least 17 Democratic and Republican senators are now sponsoring her bill to increase the number of authorized visas and take other steps to improve the efficiency of a program to help bring to the United States Afghans who helped U.S. troops. In a speech on Thursday, Biden strongly defended his decision to pull U.S. military forces out of Afghanistan, and set a target date of the end of next month for the final withdrawal of U.S. forces. read more A growing number of Biden"s fellow Democrats and Republicans in the Senate and House of Representatives have been urging his administration to do more for thousands of civilians who helped U.S. troops, often risking their lives and those of their families. read more "We have a moral imperative to act now – before it’s too late – and fulfill our promise of safety for the Afghans who stood shoulder-to-shoulder with our troops," Shaheen said in a statement. Senators co-sponsoring the bill include Democrats Dick Durbin, Patrick Leahy, Jack Reed, Mark Kelly, Kirsten Gillibrand and Tim Kaine, as well as Angus King, an independent who caucuses with the Democrats. Republicans signed on to the measure include Joni Ernst, Roger Wicker, Steve Daines, Ben Sasse, Tim Scott, Dan Sullivan, Cynthia Lummis, Rob Portman and Todd Young. Members of the House are also working on legislation to help the Afghan civilians. Many lawmakers have voiced support for evacuating interpreters and others who worked with U.S. forces to third countries to protect them while their applications for visas to reach the United States are reviewed.