House Appropriations Chairman David Obey of Wisconsin said he was leaving Congress because he was tired and it was just his time. At age 71 and after more than 40 years serving in Washington, it's easy to take him at his word.

But Obey was also feeling pressure from a national political landscape that has changed dramatically over the past year, as well as a highly touted -- and young and energetic -- GOP recruit. The National Republican Congressional Committee had even begun airing a TV ad in Obey's district.

The NRCC hit debuted on April 15, Tax Day, and told viewers if they were looking for someone to hold accountable for increased spending in Washington, "How about the architect for Obama's spending, David Obey."

Running to replace Obey on the GOP side will likely be Ashland County District Attorney Sean Duffy, a former "Real World" cast member. On the Democratic side, names already thrown into the mix include several state legislators and attorneys.

Obey's rural 7th District includes all of 17 counties in the northwestern and central portions of the state, as well as parts of three others. Its voting in presidential elections tends to mirror that of the entire state. In fact, the last three winning candidates had identical winning percentages in the district and statewide: Barack Obama, 56%-42% in both; John Kerry, 50%-49% in both; Al Gore, 47%-47% in the district, 48%-48% statewide.

In a sign of how big Obey's retirement is, the NRCC has already begun using it for fundraising. "This is more than a symbolic retirement - the Architect of the Failed Stimulus has decided he cannot justify his votes in Congress to a district that has elected him for over 40 years," NRCC executive director Guy Harrison writes in a fundraising email.