Washington • Presidential hopeful Newt Gingrich’s campaign attacked Virginia’s GOP primary-election system on Saturday for keeping him off the state’s March 6 Super Tuesday ballot. It was a significant setback for a candidate who has surged in popularity but struggled to organize his campaign.

The state party said that Gingrich, who lives in Virginia, had failed to submit the required 10,000 signatures to appear on the ballot. Texas Gov. Rick Perry also failed to qualify, the state GOP said.

The Gingrich campaign responded that “only a failed system” would disqualify Gingrich and other candidates. It said Gingrich would pursue an aggressive write-in campaign, although state law prohibits write-ins on primary ballots.

“Voters deserve the right to vote for any top contender, especially leading candidates,” Gingrich campaign director Michael Krull said in a statement. “We will work with the Republican Party of Virginia (RPV) to pursue an aggressive write-in campaign to make sure that all the voters of Virginia are able to vote for the candidate of their choice.”

However, state law says this about primary write-in campaigns: “No write-in shall be permitted on ballots in primary elections.”

“Virginia code prohibits write-ins in primaries. He can’t do it,” said Carl Tobias, a law professor at University of Richmond.

Tobias said Gingrich may have had trouble meeting a requirement that he must submit 400 signatures from each of Virginia’s 11 congressional districts.

Gingrich’s campaign did not immediately respond to a request for comment.

Forty-six delegates will be at stake in Virginia’s Super Tuesday primary. That’s a small fraction of the 1,144 delegates needed to win the nomination. But they could prove pivotal in a close race, especially for a candidate like Gingrich, who expects to do well in Southern contests.

Gingrich already missed the deadline to appear on the ballot in Missouri’s Feb. 7 primary, though he insists it doesn’t matter because the state awards delegates based not on the primary but on a Republican caucus held in March.

The setback in Virginia comes days before the Jan. 3 caucuses in Iowa, the leadoff contest in the campaign for the Republican presidential nomination.

Gingrich began rising in polls in early December, renewing his hopes of competing late into the primary season with chief rival Mitt Romney, the former Massachusetts governor.

He has tried to use the surge in popularity to make up for a late start in organizing his campaign. That Gingrich and Perry failed to get on Virginia’s ballot underscored the difficulty that first-time national candidates — many with smaller campaign operations and less money — have in preparing for the long haul of the campaign.

It also illustrates the advantage held by Romney. He has essentially been running for president for five years, and his team, smaller than in 2008 but larger than those of most of his 2012 opponents, has paid close attention to filing requirements in each state. He will appear on the Virginia ballot, along with Texas Rep. Ron Paul, who also has run a national campaign before.

Ironically, Gingrich had a slight lead over Romney in a Quinnipiac poll of Virginia Republicans released earlier in the week.

Virginia GOP spokesman Garren Shipley said in a statement that volunteers spent Friday validating petitions that the four candidates submitted by the 5 p.m. Thursday deadline to the State Board of Elections. Shipley did not respond to telephone calls Saturday seeking comment.