Obama seeks 'fast track' trade win in Senate vote Tuesday, but many more battles will follow

A much-anticipated Senate vote on trade will pack some suspense Tuesday. But it won't be the final word no matter how it turns out.

Supporters of President Barack Obama's trade agenda need 60 votes in the 100-member Senate merely to start a full-blown debate on the legislation.

Falling short would wound their pride. But it's virtually certain they would try again this year, possibly under better conditions.

Starting the full debate this week is no guarantee of success, however. Labor unions and others vehemently oppose the legislation.

Obama seeks "fast track" authority that would let him present Congress with proposed trade agreements it can ratify or reject, but not amend.

If successful, he's likely to ask Congress to approve a long-negotiated Pacific Rim trade accord with 11 other nations.