KABUL —  Sen. John McCain called Tuesday for more American troops in Afghanistan, saying that doubling the number of Marines in one southern region could lead to “significantly more success.”

The former Republican presidential candidate, along with other members of a visiting congressional delegation, also said that Afghanistan’s elections this week were a milestone event….

The group’s two-day visit included meeting with Marines in southern Helmand province, where U.S. and Afghan forces are staging a major offensive aimed at clearing out Taliban militants ahead of Thursday’s vote.

The visit comes as Gen. Stanley McChrystal, the top U.S. and NATO commander in Afghanistan, is working on a review of the Afghan war strategy. President Barack Obama has already ordered additional deployments that will put a record number of U.S. troops in Afghanistan by year’s end.

McCain declined to say exactly how many more troops he thought were needed before learning the general’s views on how the war is going, but he did say more troops were need in Helmand, the world’s largest opium-poppy growing region.

“There are three Marine battalions now in Helmand. I think it’s very clear that if they had six Marine battalions, there they would enjoy significantly more success,” the Arizona senator said, adding that additional Afghan troops were needed, too. There are roughly 3,000 troops in a battalion.

Already, the White House ordered 21,000 additional U.S. troops to Afghanistan this year, bringing the total by the end of 2009 to a record 68,000. Combined with other NATO troops, more than 100,000 Western forces will be in the country.

Also on the trip were Sens. Joe Lieberman, an independent from Connecticut, and Susan Collins, a Republican from Maine.