In a staggering turn of events, former state Rep. Jon Keyser failed to make the Republican primary ballot for the U.S. Senate seat held by Democratic incumbent Michael Bennet, falling just 86 signatures short, state officials announced Monday afternoon.

Within minutes, a spokesman for Keyser said the campaign plans to appeal the decision in court.

“We are confident that we secured the necessary number of signatures to appear on the ballot and we will be pursuing legal action to ensure thousands of Coloradans are not disenfranchised,” said Matt Connelly, Keyser’s communications director.

Candidates have five days after a ruling on petitions to file an appeal in Denver District Court. A spokeswoman for Secretary of State Wayne Williams said the office hopes Keyser files right away, as the office is on a tight deadline to set the primary ballot.

An attorney who reviewed the ruling said he was confident the secretary of state’s office made several errors, a source close to the Keyser campaign told The Colorado Statesman.

Keyser, a major in the Air Force Reserve, left Saturday for military duty in Florida and was unable to comment, his campaign said.

Colorado law requires that candidates turn in 10,500 valid signatures — 1,500 from each of the state’s seven congressional districts — in order to make the statewide primary ballot. Keyser turned in 16,067 signatures, and state elections officials ruled that 11,436 of them met requirements, but he fell 86 signatures short in the 3rd Congressional District.

It’s the latest twist in a tumultuous primary that has seen plenty of surprises, from several prominent Republicans passing on the race to an early frontrunner, staunch conservative state Sen. Tim Neville, R-Littleton, losing a bid for the primary ballot through the caucus and assembly process to a little-known county official. Keyser, a decorated veteran whose campaign has focused on national security issues, has been considered a top candidate since word of his potentially well funded candidacy broke in December.

So far, just two Republicans have made the June 28 primary ballot for the chance to challenge Bennet, seen as the only vulnerable Democratic senator up for reelection this year. El Paso County Commissioner Darryl Glenn was the lone candidate to make the primary earlier this month at the state GOP assembly, where he won the support of just over 70 percent of delegates and kept nine other candidates from a spot on the ballot. Jack Graham, a former Colorado State University athletic director, qualified for the ballot by petition last week.

Two other candidates — Colorado Springs businessman Robert Blaha and former Aurora City Councilman Ryan Frazier — have also submitted petitions and should learn whether they make the ballot by the end of the week.

Republican congressional candidate Eric Weissmann successfully challenged a similar ruling that his petition signatures were insufficient in 2012 when a district court judge agreed that hundreds of signatures should have been counted despite clerical errors on petition gatherer affidavits and notarizations. Although he won a spot on the 2012 primary ballot, Weissmann lost the election for the 2nd Congressional District nomination to state Sen. Kevin Lundberg, R-Berthoud, who went on to lose in November to U.S. Rep. Jared Polis.

According to an analysis of the rulings on Keyser’s petitions, 277 signatures were rejected because the circulator affidavit was incomplete, 479 signatures were rejected because of incorrect information about the petition circulator, 208 signatures were rejected because the notarization was incomplete, and 110 signatures were rejected because the circulator and notary used different dates. The biggest chunk of rejected signatures, totaling 1,184, were thrown out because the signer wasn’t registered as a Republican, as state law requires. Just 467 signatures were rejected because the signer had already been counted on Graham’s petitions, because the law says a voter may only sign a single petition for each office. (A small number of each of the petition signatures referenced above included multiple reasons for rejection.)

— ernest@coloradostatesman.com