Former Rep. Rob Portman (R-OH) has officially announced his campaign for Senate this morning, running for the seat of retiring GOP Sen. George Voinovich.

Portman brings a few strengths to the race. For one, his campaign committee still has $1.5 million, which can be rolled over into the Senate race. And he remains popular in the Cincinnati area from his 12 years in the House, which could help him in a Republican primary if any of the other other GOPers that have been mentioned -- including former Rep. John Kasich and former Sen. Mike DeWine -- decide to get in.

On the other hand, Portman has some clear vulnerabilities because of his work in the Bush Administration. Portman left Congress in 2005 to be U.S. Trade Representative, and later became the White House Budget Director. In a state where the economy is always the biggest issue, and free trade is very unpopular, expect the Dems to hammer him on this stuff if he becomes the nominee.