Republican U.S. Senate candidate Jack Graham submitted nominating petitions for the June primary ballot to the secretary of state’s office Monday morning, beating three other GOP Senate candidates who are also hoping to secure a spot in the primary by petition.

“We’re pretty happy to be first and a week before the deadline,” said Graham campaign manager Dick Wadhams. “We checked every signature, and we had a comfortable cushion above the 1,500 (signatures required) in each congressional district.”

It could be well into April before secretary of state officials determine whether Graham’s petitions qualify him for the ballot, officials said, after a painstaking review to determine whether enough signatures are valid.

Graham is among 13 Republican candidates seeking the nomination to take on Democrat Michael Bennet, considered the lone vulnerable Senate Democrat on the ballot this fall.

The other Republican Senate candidates seeking the ballot via petition are Colorado Springs businessman Robert Blaha, former Aurora Councilman Ryan Frazier and former state Rep. Jon Keyser, R-Morrison.

To make the June 28 ballot, candidates must turn in 10,500 valid signatures from Republicans, with 1,500 from each of the state’s seven congressional districts.

The Graham campaign had some volunteers circulating petitions but mostly relied on signatures gathered by Kennedy Enterprises of Colorado Springs, Wadhams said.

The deadline to turn in petitions is April 4.

Another nine GOP candidates are hoping to make the ballot at the April 9 state assembly, where those who get the votes of more than 30 percent of delegates advance to the primary. Those candidates include state Sen. Tim Neville, R-Littleton, El Paso County Commissioners Darryl Glenn and Peg Littleton, Lakewood businessman Jerry Natividad, Jefferson County Commissioner Don Rosier, Air Force veteran Charlie Ehler, and activists Jerry Eller, Tom Janich and Michael Kinlaw.

Turning petitions in first can make a big difference because of the way the secretary of state’s office verifies signatures.

Unlike ballot measure petitions, which use statistical sampling to verify signatures, state law requires a ruling on every signature submitted on candidate petitions. State law also forbids voters from signing more than one petition for the same office, although the secretary of state’s office doesn’t try to determine which voters signed which petitions first, just which petition was turned into the office first. Petitions are verified in the order they’re received, and under current rules, once a voter’s signature for one office is verified, that signature can’t count for a candidate seeking the same office.

That can create problems for candidates who turn in their petitions later, because they don’t know which of their signatures won’t matter because they’re already being counted for a candidate whose petition made it to the office earlier.

A spokeswoman for Blaha said Monday the campaign was “getting closer” but didn’t say when the campaign planned to turn in its petitions. A Keyser campaign spokesman said the campaign “look[s] forward to submitting our petitions in accordance with the deadline …” The Frazier campaign didn’t immediately respond to a an emailed inquiry Monday, but the candidate told The Statesman recently that the petitioning was on track.

— ernest@coloradostatesman.com