Millions of news cycles (and a few months) ago, Senate seats from Colorado and Iowa were not thought to be in play. But now polls have each of them in a virtual tie. In Iowa, Republican Joni Ernst has a statistically insignificant 0.7 point lead in the RealClearPolitics average over Rep. Bruce Braley, and in Colorado Rep. Cory Gardner (R) trails  incumbent Sen. Mark Udall, also by an insignificant amount (1 point in the RCP average).

Sen. Mark Udall, D-Colo., speaks on Capitol Hill in Washington.  (Susan Walsh/Associated Press)

Certainly Obamacare and a listless economy play a part, as does the president’s plummeting appeal. Dems in both states voted fornbamacare; both Republicans have pledged to repeal it. It is not surprising that third-party anti-Obamacare ads have already appeared in both states.

As for Colorado, The Post reported last week, “In Colorado, 46 percent of voters say they ‘strongly’ believe that passing Obamacare was a bad idea. . . .  In other words, many more voters are motivated by their distaste for Obamacare than by how much they like it. And the number who strongly dislike it is approaching half of all registered voters — and probably even closer to half among likely voters.”

Overall in battleground states, joint polling released at the end of June found that Obama’s approval is only 38 percent (58 percent disapprove) in the 12 competitive states and voters disapprove of Obamacare by an 18-point margin. With new attention focused on Obamacare as a result of the split decisions on the federal exchange subsidies, the Democrats are likely to face a new round of scrutiny over their support for a law so unclear that circuit court judges can’t agree on what it means.

But the most surprising factor in these two races is candidate quality. Democrats had high hopes for Rep. Braley, but his non-stop gaffes on farmers and abrasive personality have sent voters fleeing. Ernst has had a few rocky moments but has capitalized on Braley’s slips and radiates a positive, populist message. She was able to unite both tea party and establishment Republicans in her big primary win. Colorado Republicans got a high-quality candidate when Gardner not only decided to run but cleared out other Republican opposition. He’s been on the offensive — battering Udall on Obamacare and on the Keystone XL Pipeline.

Now remember, Republicans thought they had a clear path to the six Senate seats needed for a victory even without these states. Most pollsters have relatively easy pickups for the GOP in Montana, South Dakota and West Virginia. Throw in hobbled incumbents running in states Mitt Romney won in 2012 (Alaska, Louisiana, North Carolina and Arkansas) and it’s hard to see how the Democrats could hold the Senate if they lose either — and surely if they lose both — Iowa and Colorado.

True, we are four months out from the election, but are views of the economy and Obamacare going to change all that much before November? Probably not. Candidates nevertheless can falter and both Republicans will need to keep on the offensive, rebut the onslaught of attack ads coming their way and present a responsible, positive set of policies they’d be willing to support. If they do, one or both of them are likely to win (both incumbents are well below 50 percent). And with that will go the Democratic majority.