DENVER -- Most of the action on the primary ballot is on the Republican side, with the GOP set to decide its nominees for governor, three congressional seats currently held by Republicans and a handful of state legislature contests.
Here's a look at the top five storylines to keep your eye on Tuesday night.
1. The Governor's Race
Democrats and Tea Party conservatives agree on at least one thing: Tom Tancredo. The outspoken former congressman and anti-establishment illegal immigration hawk is beloved by many among the conservative base. He's also the Republican that Democrats would love to see matched up against Gov. John Hickenlooper this fall -- so much so that a Democratic independent expenditure committee has spent around $200,000 on a pair of TV ads aimed at helping Tancredo while weakening one of his rivals, Bob Beauprez.
Beauprez, who entered the race late and has used a lot of his own money to mount a campaign, is dominating the airwaves in the final stretch of the primary campaign, with his own ad running alongside one from another outside group, Republicans Who Want to Win, formed to back Beauprez. The trouble for Beauprez is that general election arguments don't often resonate with the more conservative primary electorate. On top of that, he's not the only candidate in the primary field offering a general election argument.
Secretary of State Scott Gessler has his own ad on TV reminding voters that he's the only candidate in the field who's won a statewide election; and Mike Kopp, who won top-line at the April GOP assembly and has an outside group running radio ads on his behalf, is also seeking to differentiate himself from Tancredo as a more reliable conservative who can actually unify the party.
If Tancredo is able to win Tuesday night, it won't be because he's worked the hardest or spent the most money -- he's been virtually invisible down the stretch and absent from the airwaves, content to rely on the Democratic ads working on his behalf. A Tancredo win may result from his savvy decision in April to encourage his supporters to vote for Kopp at the assembly after he'd already petitioned onto the ballot; having a third candidate to help divide the anti-Tancredo vote may turn out to be the defining tactical move of the primary campaign. Should Beauprez or Gessler both do just well enough to come in behind Tancredo, it won't mean that Republicans don't want to win in November, just that their vote was split in a way that will likely make a GOP win in the governor's race that much more unlikely.
While Beauprez's entrance into the race sucked up a lot of the money at first, Gessler has steadied his campaign and won the most recent fundraising periods on the strength of hard work securing broad support from the GOP's grassroots. And Kopp may prove to be a factor, thanks in large part to the support of conservative stalwarts like Hank Brown and Bill Armstrong.
If Beauprez, Gessler or even Kopp can garner enough support to win the nomination, it'll bolster the chances of the Republican U.S. Senate candidate, Congressman Cory Gardner, who will have a harder time appealing to the political center this fall if he's atop the GOP slate with Tancredo. Given Hickenlooper's poll and fundraising numbers, many Republican insiders will be happy with a gubernatorial candidate who simply doesn't hurt Gardner. A win by Tancredo would be viewed as another primary season victory for the Tea Party over the GOP establishment -- and Colorado Democrats will be cheering it the loudest.
2. Will Ken Buck follow Cory Gardner in CD-4?
Nothing encapsulates the current dynamic within the conservative base, not to mention the landscape in Colorado's deeply red fourth congressional district, better than the fact that Ken Buck, in a four-person primary field, is the de facto establishment candidate. Yes, the same Ken Buck who rode the Tea Party wave to the GOP's U.S. Senate nomination in 2010; the same Buck who lost that year's race in November after Democratic Sen. Michael Bennet capitalized on his deeply conservative positions on social issues -- support for personhood, his famous comparison of homosexuality to alcoholism on NBC's Meet The Press -- to render Buck "too extreme" for suburban women voters.
Somehow, three Republicans are challenging Buck -- from the right: outgoing state Sen. Scott Renfroe, who won top line at the district assembly in June after reminding delegates that Buck tried to soften his stance in support of personhood back in 2010; Weld County Commissioner Barbara Kirkmeyer, who helped spearhead last year's 51st State secession initiative in 11 rural Colorado counties; and former Cranston, Rhode Island Mayor Steve Laffey, who's pumped $350,000 of his own money into an aggressive media blitz and who boasts an endorsement from 2012 presidential hopeful Herman Cain.
Buck appears to be the front-runner, thanks mostly to his strong name ID. Renfroe's recent campaign mailer attacking all three of his rivals and asserting that he's the purest conservative in the field isn't what you do when you're ahead.
In a primary in such a conservative district, it's always possible that voters are seeking the most ideologically pure candidate; and, in this case, whichever Republican emerges from Tuesday's primary will be all but assured of a seat in Congress come January.
If Renfroe or another candidate defeats Buck Tuesday night, it'll be yet another cautionary tale reminiscent of House majority leader Eric Cantor's recent defeat, a familiar story of how Republican candidates who move ever so slightly toward the political center risk rejection by conservative primary voters in favor of even untested, unknown candidates promising purity.
3. Will Lamborn and Tipton survive?
Very few people saw Cantor's loss earlier this month to economics professor Dave Brat coming; should Congressman Scott Tipton, R-Grand Junction, somehow lose to David Cox, it would be an upset of equally stunning -- although far less significant -- proportion. No one will be talking about this race unless Cox pulls the upset, in which case everyone will be talking about it.
In Colorado Springs, Congressman Doug Lamborn again faces a primary challenge. This scenario runs counter to the 2014 narrative in that the incumbent Republican isn't being challenged by an opponent attacking the incumbent from the right. In Colorado's fifth congressional district, the most conservative district in the state, Lamborn is being challenged by Bentley Rayburn, a retired Air Force general and relative moderate compared to Lamborn.
Lamborn, who holds a big fundraising edge, is expected to prevail, despite attacks from Rayburn that he's done little in Congress.
4. Can the RMGO slate take JeffCo?
Rocky Mountain Gun Owners has a long track record of helping conservative candidates take out establishment Republicans in state legislative primaries; and this year, they're fighting hard to do just that in Jefferson County, the state's bellwether county.
The organization is backing Laura Woods, a strong supporter of personhood and school vouchers who was involved in last year's effort to recall former state Sen. Evie Hudak, while business organizations and establishment Republicans are supporting Lang Sias, a former Top Gun pilot who they believe is actually capable of winning this toss-up district come November.
RMGO is also supporting newcomer Tony Sanchez, who just moved to Colorado last year, over attorney Mario Nicolais, who's been attacked for his support of civil unions. Because business groups haven't put money behind Nicolais's bid they way they've helped Sias, Sanchez may be the favorite in this primary match-up, despite Nicolais's roots in the district; and that's good news for Democrats, who see Sanchez as a much easier opponent for Sen. Andy Kerr come the fall.
With Democrats holding a precarious 18-17 majority in the senate, control of the chamber will hinge on a handful of races; and many political observers believe that Republicans chances of winning a majority in November will take a big hit should Woods and Sanchez both prevail Tuesday night.
5. The fight to replace Ferrandino
On Tuesday night, most Democrats will sit back with their popcorn and root for Republicans to self-destruct. But there is one race on their side that is drawing some interest, the fight to follow outgoing Speaker Mark Ferrandino in House District 2.
It's a generational battle more than it is an ideological one between Alec Garnett, 31, the son of Boulder County District Attorney Stan Garnett and the former executive director of the Colorado Democratic Party, and Owen Perkins, 50, a teacher, writer for MLB.com and true bleeding heart liberal who won the endorsement of the late Ken Gordon, who died in December, for his commitment to ridding politics of outside money.
Ferrandino is backing Garnett, the establishment's choice and a fresh face viewed as an up and comer within the party. But primaries on the left aren't always that different from those on the right and can potentially be decided by the most ardent activists, for whom Perkins may hold some appeal.
Whoever wins is a shoe-in to win the general election in November, given the district's strong leftward lean.