Democrats have lurched from one potential candidate to another in a so far fruitless quest to find a challenger to Isakson, who is seeking a third term after disclosing in June that he has Parkinson's disease.
A range of well-known veteran Democrats, including former Rep. John Barrow and ex-Atlanta Mayor Shirley Franklin, have passed on a bid. So have several considered to be rising stars in the party, such as Jason Carter, who ran for governor in 2014, and state Rep. Stacey Evans.
Even lesser-known contenders, including the Rev. Raphael Warnock and Michael Sterling, an official in Atlanta Mayor Kasim Reed's administration, have opted against a challenge after publicly wrestling over whether to run.
Any Democrat who challenges Isakson will face daunting odds in Georgia. The 71-year-old enjoys high name recognition, popularity across the aisle, solid relations with black leaders and more than $5 million in his campaign coffers.
But Isakson has also faced questions about his health since he revealed in June that he has suffered from Parkinson's for about two years. He has since maintained that the disease was in its earliest stages and that it would not jeopardize his ability to serve another six-year term.
With less than two months to go until qualifying, he's only attracted one known challenger: Republican Derrick Grayson, a MARTA engineer and minister who garnered 1 percent of the vote in the 2014 Senate primary. His campaign, though, was disbanded by the feds in November.
There's not much wiggle room left for Tarver or another contender. Democrats have until early March to find a candidate.