We know Kirk Cousins is the Broncos’ first choice.

But what happens if they don’t get him? Cousins tentatively will have at least three other choices once free agency opens March 14: The New York Jets, Arizona Cardinals and Minnesota Vikings.

Plan B for the Broncos could well be Case Keenum. A league source told 9NEWS the Broncos are one of four teams that are expected to be in on Keenum when the NFL free agency opens. The other three teams also expected to be interested in Keenum, according to the source, are the Cardinals, Vikings and Cleveland Browns.

PHILADELPHIA, PA - JANUARY 21: Case Keenum #7 of the Minnesota Vikings reacts during the fourth quarter against the Philadelphia Eagles in the NFC Championship game
Patrick Smith, 2018 Getty Images

So, the Broncos, Cardinals and Vikings could be juggling two big offers to the two most attractive free-agent quarterbacks as the market rolls open next week. As they should. Cousins can only pick one team.

More teams could get involved come the free-agent “soft opening” on March 12 or even March 14 when free agency officially begins.

A veteran free agent -- the Broncos may also be interested in various degrees with Josh McCown and Teddy Bridgewater if they become available – is expected to be general manager John Elway’s first choice.

But the mega-physical talent that is Josh Allen may be moving up on the pecking order.

The Broncos took a long look at all the young quarterbacks here at the NFL Combine. They’re all different. Different styles of quarterback play. Different personalities.

To me, Josh Allen is the most real guy. Maybe, because he has the humblest of roots.

“I mean, I was at junior college,’’ Allen said during his NFL Combine press conference. “I was begging teams to get me a scholarship, sending emails out and hoping to hear back from them and I got one opportunity, that was with the University of Wyoming, thankfully, and they gave me an opportunity and I took advantage of it.’’

The most authentic was Lamar Jackson. He doesn’t even have an agent.

“I know coming in as a rookie, an agent doesn’t really negotiate anything,’’ he said. “You’re going to get the salary you’re going to get. Or whatever. I decided I don’t need him. He’s going to be taking a big cut of my pay check any ways. And I feel I deserve it right now.”

There had been some less-than-flattering things going around about Josh Rosen’s personality. But I came away impressed.

“You address it here,’’ Rosen said. “I think that’s why all these interviews and meetings and visits are awesome, because teams actually get to know me and they don’t have to find out through third parties.’’

Sam Darnold was not as confident as I thought. Baker Mayfield was confident times 10.

The two young quarterbacks who would make the most sense for the Broncos: Josh Allen and Baker Mayfield. Mayfield because of his spunk and ability to move around. Allen because he has John Elway-like talent.

Allen lit up the Combine through his passing and athletic drill feats Saturday. Broncos coaches Bill Musgrave, Mike Sullivan and Klint Kubiak would have to work on Allen’s accuracy on routes between the hashes.

But it probably wouldn’t be easy for Elway to pass on this type of quarterback specimen if Allen is there with the No. 5 overall draft pick.