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“I think we’re in a phase now, and it may last a little while, but the fortunes of the parties ebb and flow,” said Karl Kurtz, a political scientist at the National Conference of State Legislatures. “The one constant about American politics is that voters change.”

He noted that the danger for any one-party state is overreach, and some legislators already are feeling the heat for pushing through too many bills relying on one party’s dominance of the levers of state power. In Colorado, recall campaigns organized by gun rights advocates have turned in signatures aimed at ousting two Democrats, Senate President John Morse and state Sen. Angela Giron, for their votes in favor of gun control bills.

A Quinnipiac University poll released last week found that 49 percent of voters surveyed disapprove of the Colorado legislature’s performance, while 36 percent approve.

“Colorado Democrats are showing the same hubris as Republicans did 10 years ago,” said Denver-based Republican Party strategist Dick Wadhams. “The Democrat legislature is not popular, so I think the potential for a Republican comeback is there.”

Midwestern Republican governors such as Scott Walker of Wisconsin and John Kasich of Ohio have had their agendas challenged as they moved to cut the power of public-sector unions. Mr. Walker survived a celebrated recall battle in June 2012, although some Republican state lawmakers were ousted.

The first Republican-dominated state government in more than a century in North Carolina is now the target of so-called Moral Monday weekly protests in Raleigh, led by liberal clergy members, teachers unions and environmentalists. Reuters news agency reported that almost 600 people have been jailed in the past eight weeks of protests in Raleigh, including 120 — the most so far — this week.

“They may have the votes, but we have our voices and our bodies,” the Rev. William Barber, president of the state NAACP chapter, said at Monday’s protest. “We are sowing a seed of resistance that will come up in communities all across this state and nation.”

But Tar Heel State Republicans appear to be standing their ground on issues such as tougher voter ID laws and tax cuts and resistance to President Obama’s health care law. State Sen. Thom Goolsby, New Hanover County Republican, dismissed the protests as “Moron Monday” in a biting op-ed this month.

“The circus came to the State Capitol this week, complete with clowns, a carnival barker and a sideshow,” he wrote in the Chatham Journal.

Political control in closely divided states such as Colorado may continue to swing between the parties, but analysts also say the blue-red divide is likely to become the norm for most of the country for the foreseeable future.

“A lot of these one-party states are going to remain that way for some time, like Utah and Idaho on the Republican side, or Massachusetts and Vermont on the Democrat side,” said Mr. Wadhams. “There used to be moderate Republicans in the Northeast and centrist Democrats in the South, but there’s really no such thing as a liberal Republican or a conservative Democrat anymore.”