Colorado Democrats are about to learn the wisdom of spending $4 million to meddle in today's GOP Senate primary. Calling Ron Hanks a true conservative and questioning if Joe O’Dea is even a Republican may give them a weaker nominee to fight off — or it could strengthen the rival they feared.

Driving the news: Voters head to the polls Tuesday to pick candidates in Colorado, Illinois, New York, Oklahoma and Utah. Sen. Michael Bennet (D-Colo.) isn’t among the most vulnerable Democratic incumbents. But with inflation surging and President Biden’s approval ratings in the low 40s, party strategists worry how many incumbents could get wiped out in a wave election.

• Democrats would rather see Bennet face Hanks in November, so they've spent big to boost Hanks' chances with GOP primary voters.
• But if O'Dea wins, their efforts to highlight his past support of Democrats — and make him appear GOP-lite — might improve his chances against Bennet by inoculating him on issues like guns, partisan gridlock, and even abortion.

The big picture: Across the country, heavy spending by Democrats to drag (potentially) unelectable Republicans across the primary line has accelerated this cycle.

• The risk is twofold. Candidates who questioned the legitimacy of Joe Biden’s election can be swept into office in a wave year. And if the more moderate candidate squeaks through, swing voters may remember in November that they were the non-MAGA candidate.

How we got here: Bennet is running for a third term in a state Biden won by more than 13%. But after Republican Glenn Youngkin won in plus-11 Virginia, Democrats looked across the map to reassess who else might have a tighter-than-expected race in 2022.

• They don't want Bennet to face O’Dea, a first-time candidate who was adopted at birth by a working-class family and supports some abortion rights. The founder of a successful construction company, O’Dea has given $1.6 million to his own campaign.
• The goal is to engineer a victory for Hanks, a state representative who marched to the Capitol on Jan. 6, opposes abortion in all circumstances and has questioned Biden’s legitimacy.
• Hanks has raised just $125,000 on his own, but with the dark-money Democratic cash infusion, strategists from both parties say the race is too close to call.

By the numbers: An outside super PAC called Democratic Colorado has run some $2 million in ads highlighting Hanks' greatest conservative hits.

• In mid-June, the group also went up with a $2 million dollar buy against O’Dea that could have been scripted by the Hanks campaign, with O'Dea side-by-side with Biden and highlighting his donations to Bennet and Sen. John Hickenlooper (D-Colo.)

Reality check: It’s only June. While some voters might think of O’Dea as a centrist Republican now, most general election voters haven’t tuned into the race yet.

• During the primary, Democrats have harvested quotes and comments from O'Dea on everything from gun control to Colorado’s abortion rights legislation.
• The Supreme Court's repeal of Roe v. Wade might energize suburban swing voters in Colorado, which was deeply anti-Trump, to vote against Republicans.

What they are saying: Patrick Burgwinkle, a spokesman for the Democratic Senatorial Campaign Committee, said the primary has left O'Dea as well as Hanks "saddled with an agenda that is totally out of step with the voters that decide the general election in Colorado," and “we are prepared to defeat whichever candidate limps out."

• Justin Lamorte, Bennet’s campaign manager, said the GOP rivals were "spending down their resources and racing far to the right of Coloradans," while Bennet "is campaigning hard," opening grassroots offices and setting fundraising records.
• “We are an organization committed to ensuring that Colorado doesn’t elect a Republican to the U.S. Senate,” said Alvina Vasquez, a spokesperson for Democratic Colorado.

The other side: "Nothing in life has ever been given to me," O'Dea told Axios. "I never met my biological parents. My adopted parents made me wash dishes to pay for parochial school. My business has survived three recessions."

• "We are up for the fight," he said. "I’m not afraid of [Democratic Senate Majority Leader] Chuck Schumer. I’m going to beat him in the primary and the general."
• "Democrats have made clear what we’ve known all cycle: Michael Bennet is vulnerable," said Chris Hartline, a spokesperson for the National Republican Senatorial Committee. "His 100% support for Joe Biden’s inflation-inducing, gas-price raising, border-crisis creating agenda is coming back to haunt him."