Updated

Republican presidential candidate Rick Santorum said Friday he will fight an Indiana election board's ruling that he does not have enough support to appear on the state ballot in the May 8 primary.

All statewide candidates are required to obtain 500 valid signatures from each of the state's nine congressional districts in order to be placed on the ballot. The Marion County Board of Elections has ruled that Santorum fell 24 signatures short in Indiana's 7th District.

Santorum told reporters in Missouri that he is challenging the ruling. Indiana supporters say the board incorrectly threw out 200 signatures submitted by the campaign.

"We've got some very credible, I'm sure, solid legal challenges and I have no doubt that we'll be on the ballot there," Santorum said.

The Indiana Republican Party says former House Speaker Newt Gingrich, Texas Rep. Ron Paul and former Massachusetts Gov. Mitt Romney have all gathered enough signatures to qualify for the primary.

Santorum managed to get enough signatures to make the ballot in the state's eight other congressional districts. But he said Friday that confusion over whether the signatures had to be collected in the current 7th District or the redrawn district, which removes a large chunk of northern Marion County, added to his campaign's troubles.

Santorum supporter Mike Delph, a Republican Indiana state senator, tweeted Friday that the campaign would do everything possible to get on the ballot.

"The Santorum campaign has not conceded anything in Indiana and will exercise all of its options to overcome the 24 signature deficit in D7 (District 7)," Delph wrote on Twitter.