From NBC's Mark Murray and Domenico Montanaro
Clinton, per her campaign, has just picked up her second labor union endorsement this week -- from the International Association of Machinists and Aerospace Workers. The endorsement comes a few days after some of the Democratic presidential candidates (including Clinton, Edwards, and Kucinich) spoke to the union. The IAM also endorsed Huckabee in the GOP race.

Earlier this week, Clinton also won the United Transportation Union's endorsement.