Weeks of technical problems with the health insurance enrollment website and anxiety over insurance cancellations for millions of people have erased early advantages enjoyed by Democratic candidates Gary Peters in Michigan and Mark Udall in Colorado.
As the election year dawns, those problems have widened the narrow opening for Republicans to retake control of the Senate.
"There's not a lot of wiggle room here. Colorado is definitely in play," said Craig Hughes, a Denver-based Democratic consultant who ran Obama's 2012 Colorado campaign and Democratic Sen. Michael Bennet's 2010 campaign. "The website was a disaster, and the process of changing insurance is inherently difficult. This is not going to be a smooth process."
Republicans need to pick up six seats to win the Senate in a midterm election year that typically hurts the party in the White House.
A victory in either Michigan or Colorado — both carried by Obama in 2012 and 2008 — would greatly boost their chances. Democrats already are defending Senate seats in seven states that Obama won, including three where incumbents are retiring.
Peters, a third-term congressman, and Udall, a first-term senator, both voted for the 2010 health care bill. They echoed Obama's often repeated but now discredited statement that people who had health insurance before the law took effect could keep it if they were satisfied.
By mid-November, 4.2 million Americans had received insurance cancellation notices, according to an Associated Press review, including at least 225,000 in Michigan.
Not even 7,000 Michigan residents had enrolled through the federal insurance exchange as of Nov. 30, according to U.S. Department of Health and Human Services. That number is expected to increase, but the early glitches kept sign-ups well below expectations.
At the same time, unemployment in Michigan hovers above the national average, and its biggest city, Detroit, is in bankruptcy. Democrats are fighting to reverse the historic drop-off in Democratic voter turnout in midterm elections, a problem that's compounded by the fact that Republican Gov. Rick Snyder, who's also on next year's ballot, is polling well ahead of his little-known Democrat challenger, former U.S. Rep. Mark Schauer.
In Colorado, at least 106,000 people had received cancellation notices as of mid-November, while fewer than 10,000 had enrolled in the state-run health insurance exchange. Colorado's economy has performed better than Michigan's, but Democratic Gov. John Hickenlooper, who's also seeking re-election in 2014, has come under fire from the right for his efforts to enact new gun restrictions and to allow gay marriage.
To be sure, Republicans have not seized control of the contests in either state. Some national GOP strategists grumble about the quality of their party's candidates, including Ken Buck in Colorado, who lost his 2010 Senate race to Bennet and is one of three candidates seeking the nomination.
Obama announced Friday that insurance sign-ups have soared across the country in December, following upgrades to the website. The administration also has taken steps to help the 500,000 consumers with canceled policies who have yet to secure new coverage.
Still, recent public polls have shown Peters running even with Republican Terri Lynn Land, a former Michigan secretary of state, in the race to succeed retiring Democratic Sen. Carl Levin. Udall's approval in Colorado also has fallen into territory considered vulnerable.
During a campaign swing last week, Peters defended his support for the health law, and refrained from attacking Land for backing House Republicans' October shutdown of the federal government in their fight to defund the law.
"This bill gets us down the road but we've got to keep working on it," Peters said in an interview after a campaign event in Kalamazoo. "This is an election about someone who just wants to repeal the law and has no alternative and someone who is rolling up his sleeves."
Land said she plans to use Peters' claim that policyholders will not lose their coverage as a main campaign point. "When you make that promise, and you don't deliver, it really goes to the credibility," she said.
The policy cancellations broadly link Peters and Udall, as well as other Democrats, to cracks appearing in public perceptions of Obama. Just 42 percent of Americans approve of the job he's doing, according to an Associated Press-GfK poll this month. The poll found 56 percent of Americans said the word "honest" does not describe Obama well.
In Kalamazoo, in GOP-heavy western Michigan, perceptions of the health care law and its impact on the Senate race depend on who you ask.
"These issues can be fixed," said Lucy Bland, director of a food co-op kitchen.
"It going to set us all back for a long time," countered Kevin McLeod, with the area Chamber of Commerce.
Democratic National Committee leaders say publicly they welcome election-year attacks on the health care law, and plan to respond by pointing to the October shutdown. By next fall, they contend, the contour of the Michigan and Colorado Senate races will look more like 2012.
"None of these races have had their fundamentals change" due to problems with implementation of the health care law, said Justin Barasky, spokesman for the Democratic Senatorial Campaign Committee.
But Republican strategist Charlie Black notes that former President George W. Bush's believability slipped below 50 percent in November, 2005, a year before Democrats retook control of both houses of Congress. He said voters began questioning Bush's honesty and competence after the failed federal response to Hurricane Katrina that year.
"Obamacare gives both these negatives to Barack Obama," Black said.