By Liz Marlantes | Staff writer of The Christian Science Monitor

WASHINGTON – More than a week after the Republican National Convention - and in the wake of new questions about President Bush's National Guard service - the race for the White House is once again tightening, just as pollsters and strategists for both campaigns had predicted it would

A new Monitor/TIPP poll finds Mr. Bush and Sen. John Kerry currently tied among likely voters nationwide, with each receiving 47 percent of the vote in a two-man race, and each receiving 46 percent when independent candidate Ralph Nader is added to the ballot. The poll of 674 likely voters was conducted Sept. 7-12, and has a margin of error of 4 percent.