WASHINGTON – Congress emphatically approved legislation Friday preserving jobs on transportation projects from coast to coast and avoiding interest rate increases on new loans to millions of college students, giving lawmakers campaign-season bragging rights on what may be their biggest economic achievement before the November elections.

The bill sent for President Barack Obama’s signature enables just over $100 billion to be spent on highway, mass transit and other transportation programs over the next two years, projects that would have expired today without congressional action. It also ends a political battle over student loans that raged since spring, a proxy fight over which party was best helping voters muddle through the economic downturn.

Under the bill, interest rates of 3.4 percent for subsidized Stafford loans for undergraduates will continue for another year, instead of doubling for new loans beginning on Sunday as scheduled by a law passed five years ago to save money.