Mr. Martin signaled a tougher tone for the runoff, highlighting the DeKalb County CEO's statements that he voted for President Bush in 2000 and 2004.
"We have two opponents we'll face, and the Georgia voters will have to decide whether they want somebody who will stand against the Bush policies or somebody who's embraced the Bush policies -- both in this Democratic runoff and in the general election," Mr. Martin said.
Mr. Jones and Mr. Martin far outpaced former broadcast journalist Dale Cardwell, Josh Lanier and Rand Knight.
The Jones camp also appeared ready to rumble.
"This is a major victory," said Mr. Jones' campaign consultant Mike Cantone. "Jim Martin was supported by the Washington establishment."
The eventual winner faces Mr. Chambliss in the November general election.
With 79 percent of precincts reporting, Mr. Jones led with 40.4 percent, followed by Mr. Martin's 34.5 percent.
Mr. Martin raised the most money and had the backing of many of the party's leaders.
"It shows that we've put together a very strong campaign," said Martin spokesman Ellery Gould. "A lot of it has to do with who Jim is and that they know him from the 2006 campaign."
Mr. Knight, a software sales director, got endorsements from labor unions and teacher groups, two factions that often use their organizations to spur members to turn out and vote. Still, he didn't raise much money.
"We simply didn't have the kind of cash that one would typically expect a statewide race to get the message out," he said. "Our yield is extremely high when they hear the message."
Mr. Cardwell, who got 15 percent in late returns, had hoped his dozen years as a television reporter in Atlanta would give him an edge.
(79 percent of precincts reporting)