Just when it looked like Sen. Johnny Isakson could take a casual stroll to another six-year term in office, along came Michael Thurmond to ruin it.

Thurmond, who had always been reluctant to leave his job as Georgia's labor commissioner, jumped off the fence last week and said he run against Isakson in the general election.

Thurmond's late entry into the race — he made the announcement less than a week before the start of qualifying — means that Isakson won't be able to walk away with victory in November. He will have to run hard if he wants to keep his seat.

This is not to suggest that Isakson is in any dire jeopardy. The GOP incumbent has always been a very popular figure among both Republicans and Democrats, and he had more than $4.4 million in his bank account as of March 31. Thurmond has never been a fundraising juggernaut, so he will be at a financial disadvantage in this race.

Isakson finds himself in a very similar position as his Senate colleague, Saxby Chambliss, in 2008.

Chambliss also had the advantages of incumbency in a Republican-leaning state and a financial edge over his Democratic opponent. Jim Martin, who was not nearly as dynamic a campaigner as Thurmond, still held Chambliss below the 50 percent mark and forced him into a general election runoff.

With that history in mind, it was interesting to see the results of the first poll taken after Thurmond jumped into the race. Rasmussen had Isakson with a 51-35 percent lead over Thurmond. While Isakson was 16 points ahead of Thurmond in that poll, he was also uncomfortably close to dropping below the 50 percent support level that can be hazardous for an incumbent.

Isakson also is dealing with some medical issues that could have an impact on this race. He has been hospitalized twice in recent weeks, including a stay in the intensive care unit, for a bacterial infection, a blood clot in his leg and an irregular heartbeat.

The senator's office issued a statement after Thurmond's announcement that quoted Isakson, who'll be 66 this year, as saying, "I am energized and ready to run a vigorous campaign that will give Georgia voters a clear choice."

Thurmond said Isakson's medical condition was not a factor in his decision to get into the race. "I have great respect for Johnny Isakson, his health is excellent, and I look forward to engaging him in an open and honest debate," Thurmond said.

Assuming that Isakson is healthy enough to run a normal reelection campaign, there are some issues at the congressional level that can help him and hurt him.

Isakson opposed the health care reform legislation signed by President Barack Obama, a position that should put him in good standing with a majority of Georgia's voters. He is already making statements that link Thurmond to the Democratic leadership in Washington: "Georgians will get to choose whether they want someone who represents their conservative values or someone who will push the Obama-Reid-Pelosi agenda of government health care."

On the other hand, Isakson and his Republican colleagues have been opposing the Obama administration's proposal to regulate Wall Street investors, which might not play so well in a year where many Americans are unhappy about the excesses of the financial community.

Thurmond touched upon this in his announcement speech: "Because Washington and Wall Street conspired against them, working men and women are in a very desperate situation."

The odds are in Isakson's favor, but Thurmond still serves a useful purpose for Georgia Democrats. He provides a credible candidate at the top of the ticket and should prevent Isakson from getting the 65 or 70 percent of the vote he would have received against a fringe opponent. Keeping Democratic support in line for this race will help the party's nominee for governor.

As an eloquent, African-American politician who has won three statewide campaigns for labor commissioner, Thurmond can generate an increase in turnout by black voters, a factor that also helps the Democratic nominee for governor.

Thurmond is "taking a bullet for the team" by agreeing to run against Isakson. There's only a small chance that he could actually win it. But even if he loses, Thurmond helps Democrats in other races.

Tom Crawford is the editor of The Georgia Report. His column appears Wednesdays and on gainesvilletimes.com.