Image caption Newt Gingrich earned a reputation for aggressive partisanship during his time as House Speaker

Newt Gingrich, one of the leading US Republican presidential candidates, has said Virginia's electoral system is flawed, after failing to qualify for the primary ballot in his home state.

Virginia party officials say he did not submit the required 10,000 signatures to appear on the 6 March ballot.

Mr Gingrich's team vowed to pursue an "aggressive write-in campaign" - although Virginia does not permit this.

Gingrich critics say the setback shows serious lack of organisation.

Four other presidential Republican candidates - including Texas Governor Rick Perry - failed to qualify for the Virginia ballot.

Only ex-Massachusetts Governor Mitt Romney, another leading candidate, and Texas Congressman Ron Paul qualified.

The Gingrich campaign submitted 11,050 signatures, but the state party later said that a review showed he did not have enough verified papers.

The campaign's director, Michael Krull, replied by saying: "Only a failed system excludes four out of the six major candidates seeking access to the ballot.

"Voters deserve the right to vote for any top contender, especially leading candidates.

Mr Krull added: "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."

It remains unclear how Mr Gingrich - a former House of Representatives speaker - intends to do this as Virginia does not allow write-ins in primary ballots.

A write-in candidate is a contender whose name does not appear on the ballot, but for whom voters may vote nonetheless by writing in that person's name.