Colorado voters will send seven members to Congress after the November election, but even though challengers are mounting enthusiastic campaigns across the state, just two of the seats appear to be in play – the 6th and 3rd congressional districts – and only the 6th Congressional District has attracted the kind of activity and spending that marks an up-for-grabs battleground.

The state’s five other congressional districts are more firmly in the hands of one party or the other, though the Democrats running in the heavily Republican 4th and 5th districts have mounted more vigorous and well-funded campaigns than the Republicans running in the 1st, 2nd and 7th Congressional Districts.

By most accounts, control of the U.S. House of Representatives runs through the 6th District in Aurora and surrounding Denver suburbs, where voters in one of the most competitive House districts in the country will either return Republican Mike Coffman to Congress for a sixth term or elect his Democratic challenger, attorney Jason Crow.

The 6th District, nearly evenly divided politically and one of the most ethnically diverse districts in the country, is one of about two dozen congressional districts nationwide won in the last election by Democrat Hillary Clinton but held in Congress by Republicans – almost exactly the same number of seats Democrats need to flip in order to seize the gavel for the next two years of President Donald Trump’s term.

Coffman, who boasts an unbroken record of wins at the ballot box since first securing a legislative seat 30 years ago, has managed to gain re-election to his congressional seat by wide margins against formidable Democratic challengers in recent cycles, but polling suggests the headwinds posed by an unpopular Republican in the White House could spell an end to his streak.

Since Crow emerged from an expensive primary against a more aggressively progressive candidate, national Democrats and their allies have been training unprecedented fire on Coffman, shattering old records for outside spending in the race.

Coffman and Crow have kept pace in their fundraising, each pulling in around $2.5 million through the last reporting deadline, though their own funds are dwarfed by groups spending on their behalf.

According to Advertising Analytics, the 6th Congressional District has seen more spending on political ads – $17 million through Oct. 1 – than any other House race in the country, and it topped the publication’s list of hottest House races this week with $2.8 million in new ad buys.

Democrat Jason Crow appears in a 30-second TV ad released by his campaign on Monday, May 28, 2018. Crow is one of two Democrats running in a primary for the 6th Congressional District seat held by Republican U.S. Rep. Mike Coffman. (Via YouTube)

A big chunk of that money was spent by national Republicans attacking Crow – an Army Ranger veteran who was awarded a Bronze Star and lauded for his work helping veterans – for missing some meetings of a volunteer state veterans advisory board. But experts say the ads might have backfired, and the GOP group pulled out of the district a few weeks ago.

Coffman, an Army and Marine Corps veteran, has blasted Crow for defending “crooks and con-men,” including one convicted of defrauding the Veterans Administration.

Democrats allege that Coffman votes with the Trump administration more often than any other Colorado lawmaker, despite vowing to “stand up” to the president. Coffman’s supporters call the attack off-base, pointing to rifts between Coffman and Trump on some of the White House’s signature initiatives.

While recent polling showed Crow ahead of Coffman by 11 percentage points, political pros caution against counting Coffman out, pointing to his inroads in traditionally Democratic communities and his record helping constituents. Coffman highlighted the latter in an ad released recently that chronicles how he helped an Aurora family save their 4-year-old adopted daughter from deportation to her native Peru.

The sprawling 3rd Congressional District, which covers the Western Slope, San Luis Valley and Pueblo County, has a history of sending members of both parties to Congress but has leaned more Republican over the last decade. This time, four-term GOP incumbent Scott Tipton has had to mount a vigorous defense against Democratic challenger Diane Mitsch Bush, a former state lawmaker and county commissioner.

Although early polling showed Tipton could be vulnerable, prompting national Democrats to add the district to a list of targets and spend early in the race, the contest lately hasn’t attracted the kind of attention it’s drawn in recent cycles.

Nevertheless, Mitsch Bush has kept up the pressure on Tipton, blaming his votes for woes in the district, which is saddled with some of the highest health care costs in the nation.

But polling also shows Trump – who won the 3rd Congressional District handily – is popular with voters, so it’ll take a Democratic wave of monumental proportions to threaten the incumbent.

Elsewhere in the state, the Coloradan with the longest tenure in Congress – Democrat Diana DeGette, serving her 11th term representing the Denver-based 1st Congressional District, one of the most solidly blue districts in the country – survived an unexpectedly spirited primary challenge and remains on course to return to Washington, D.C., for another two years. She raised more than $1 million to the $13,000 brought in by her Republican challenger, motivational expert Casper Stockham.

In the race to replace outgoing U.S. Rep. Jared Polis, the Democrat who gave up his Boulder and Larimer County-based 2nd Congressional District seat after five terms to run for governor, former University of Colorado Regent Joe Neguse looks poised to become the first African-American elected to Congress by state voters. The attorney, a son of Eritrean refugees, is facing a lackluster challenge from political newcomer Peter Yu, a business consultant.

Democrat Ed Perlmutter, meanwhile, appears to be sailing to what looks like a seventh term representing the 7th Congressional District after a brief run for governor last year, even though the suburban district – covering much of Jefferson County and western Adams County – could be considered a swing seat in the right circumstances. His Republican challenger, salesman Mark Barrington, has taken an unconventional approach in what he’s described as a “fun” run for office, but through the last reporting period had only raised about $35,000 to Perlmutter’s $1.3 million.

The Democratic women running against GOP incumbents Ken Buck in eastern Colorado’s 4th District and Doug Lamborn in the Colorado Springs-focused 5th Congressional District have kept better pace with their opponents’ fundraising, but the districts are among the reddest in the country and are likely safe GOP seats.

Longmont veterinarian Karen McCormick has run a surprisingly strong campaign for the 4th Congressional District, which stretches from Greeley to Douglas County and covers the Eastern Plains. The Democrat has raised around $325,000 to Buck’s $425,000.

Democrat Stephany Rose Spaulding, who teaches women’s and ethnic studies at the University of Colorado Colorado Springs, has run an unabashedly progressive campaign in the 5th Congressional District. Lamborn emerged in June from an expensive, crowded brawl of a primary and had only a little more than twice the cash on hand reported by Spaulding at the last reporting deadline.