The Virginia Republican Party announced early Saturday that former House speaker Newt Gingrich had failed to gather enough signatures to run in the state’s GOP presidential primary, an embarrassing setback that underscored how far he has to go to build a fully functioning campaign organization just days before the first votes of the primary season.

Party officials said Gingrich fell short of the 10,000 valid signatures required to have his name on the ballot on “Super Tuesday,” the crucial collection of 10 primaries held March 6. His chief rival in the campaign, former Massachusetts governor Mitt Romney, submitted enough signatures, as did Rep. Ron Paul (Tex.). Gov. Rick Perry (Tex.) also failed to garner enough signatures; no other key candidate submitted signatures.

While Gingrich has surged in the polls, the major question facing his campaign is whether he will be able to match his rivals in building a sophisticated operation to get his backers to the voting booths. Romney and Paul, both of whom ran for president in 2008, have spent years building national networks.

Iowa holds its caucuses Jan. 3, followed in rapid succession by primaries in New Hampshire, South Carolina and Florida. Gingrich has a more established organization in those early voting states, but Romney has been working to build an extensive network in the states that will decide the contest if no candidate breaks out of the pack early on.

Gingrich had made a last-ditch effort to get on the ballot, with stops in Rosslyn and Richmond. His failure to do so is a significant setback in his adopted home state; a poll last week by Quinnipiac University showed that Gingrich led Romney 30 percent to 25 percent among likely Republican voters in Virginia.

Gingrich has won praise in the GOP contest as an eloquent speaker with big ideas and for being an especially strong debater with a charismatic personality. But since his original campaign effort imploded in the spring, nearly torpedoing his candidacy, he has faced constant questions about whether he can harness the money and organization to assemble an elaborate and disciplined operation.

His field staff is still small, and his Iowa campaign still has many vacancies to fill among precinct captains and caucus speakers before the Jan. 3 voting. He has been doing town-hall meetings by telephone in Iowa to recruit volunteers.

And with his campaign working in recent months to pay down its debt, he has faced rivals who have had a significant financial edge for much of the campaign. It’s unclear how much of the financial gap he has closed since his surge in the polls, but lately Gingrich has had a difficult time countering an onslaught of millions of dollars of negative advertising by his opponents.

Gingrich’s campaign has portrayed his decision not to fight back in kind as the result of his desire to run a “nice” campaign. But privately, his advisers acknowledge that the candidate doesn’t really have any option without a campaign organization, deep bank account or well-funded independent committee to combat the attacks.

Gingrich hurtled toward the front of the pack just as business executive Herman Cain suspended his campaign. A national Washington Post-ABC News poll last week found that Gingrich and Romney are each favored by 30 percent of Republicans and Republican-leaning independents, followed by Paul with 15 percent.

If the race for the GOP nomination remains close on Super Tuesday, Virginia’s 50 delegates could be an important bounty for the remaining candidates. Eleven states vote before March 6.

In a statement Saturday, Gingrich campaign director Michael Krull called Virginia’s primary rules, some of toughest in the nation, a “failed system.”

“Voters deserve the right to vote for any top contender, especially leading candidates,” he said. “We will work with the Republican Party of Virginia 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, electoral experts in Virginia said the state’s election law clearly states that voters may not write in candidates during primary elections. Gingrich may appeal the party’s decision to its State Central Committee, but Dave Rexrode, executive director of the Republican Party of Virginia, said there is not enough time to hold a meeting before the State Board of Elections meets Wednesday.

“We’re evaluating what options are out there for us,” said Gingrich spokesman R.C. Hammond.

The Virginia GOP made the announcement a little after 1:30 a.m. Saturday on Twitter, writing: “RPV has determined that Newt Gingrich did not submit required 10k signatures and has not qualified for the VA primary.”

Gingrich said earlier in the week that his team had collected more than 10,000 signatures and expressed confidence that he would be on the ballot. A Republican familiar with the Virginia process confirmed that Gingrich submitted the required number of signatures but said that not enough were valid. Of the 10,000 signatures, candidates must gather at least 400 from each of Virginia’s 11 congressional districts.

(President Obama will automatically win Virginia’s Democratic primary votes after his was the only Democratic campaign to submit signatures. Virginia is considered a crucial swing state in the presidential race. In 2008, Obama was the first Democrat to win the state’s 13 electoral votes in 44 years.)

Romney’s campaign sought to capi­tal­ize on Gingrich’s setback Saturday.

“I was surprised that several other Republican candidates failed to qualify for the primary ballot,” said Lt. Gov. Bill Bolling, chairman of Romney’s campaign in Virginia. “To meet Virginia’s demanding petition requirements, you must have an effective political organization, passionate and dedicated volunteers and widespread statewide support.”

Gingrich has stronger operations in Iowa and New Hampshire, and the Gingrich campaign says its South Carolina team is one of its best.

As Gingrich tries to catch up to his rivals in terms of organization, an independent new super political action committee, Winning Our Future, is trying to do the same on his behalf. The PAC is planning to go up on the air any day in Iowa, spokesman Rick Tyler said this week.

But Gingrich still faces challenges if he is not able to lock up the nomination early.

“We’re all at different levels of campaign organization,” Hammond said. “We are organizing our ground game as vastly and efficiently as we can.”

Staff writers Dan Balz, Amy Gardner, Anita Kumar, Philip Rucker and Karen Tumulty contributed to this report.