Democrat Jon Ossoff aimed to consolidate his party's support on Thursday as he faced increasing attacks from conservative groups claiming he has inflated his experience in Congress.

Appearing with more than a dozen Democratic state legislators, Ossoff said voters should “send a message” to Washington by flipping a suburban Atlanta district that’s been in GOP hands for decades.

“The campaign’s goal is not to get into a runoff, though we’ll be ready to fight a runoff if necessary,” said Ossoff. “The campaign’s goal is to win this election outright on April 18.”

Ossoff is one of five Democrats in the 18-candidate race, but his fundraising success and rising poll numbers have made him the surprise story of the conservative-leaning district. Republican groups have spent more than $2 million on a barrage of ads trying to paint the 30-year-old former Congressional aide as a stooge of Nancy Pelosi who is in over his head.

The attacks center on Ossoff's Capitol Hill record. He has repeatedly said he was a national security staffer for five years on Capitol Hill working for Rep. Hank Johnson, and his campaign this week issued a timeline saying he had "top-secret" clearance for about five months of that time.

The conservative American Rising PAC seized on the

accusing him of falsely claiming he had top-secret clearance for all five years, though there is no evidence he ever made that assertion.

At his event Thursday, Ossoff called the criticism a “partisan smear by Washington super PACs” and said he worked for Johnson for five years “to keep our country and our state safe" with the military and intelligence agencies.

“I was granted a top-secret clearance by the U.S. Department of Defense to work on particularly sensitive programs,” said Ossoff. “I stand by my record – I will put up my national security qualifications and credentials against anyone else in this race.”

Republicans are increasingly fighting over what appears to be one slot in a likely June 20 runoff between the two top vote-getters to represent the district, which spans from east Cobb to north DeKalb.

Rival candidates see Ossoff, with a "Make Trump Furious" campaign and more than $3.5 million in contributions, as a shoo-in for the other spot. But his hopes for an outright win to avoid a runoff are much dimmer; most polls show him hovering around the 40 percent mark.

Insider's note: This was ripped and expanded from the Morning Jolt.

More AJC coverage of the Sixth District race:

An 18-candidate debate shows how jumbled Georgia special election is

Republicans, Democrats target Ossoff in Georgia special election

How outside forces play an outsized role in Georgia’s 6th District race

House GOP health care plan divides Sixth District candidates

Jon Ossoff rattles conservatives in race for Georgia’s Sixth

Watch the American Rising video: