DENVER — The Colorado and North Carolina state legislatures were unusually productive in 2013, thanks to the only thing they may have in common: one-party rule.
Polar opposites ideologically, Colorado Democrats wielded the same unchecked control this year over state government in Denver as North Carolina Republicans did in Raleigh, with predictable results. In Colorado, the upshot was a legislative session marked by sweeping new laws on gun control, election reform and benefits for illegal immigrants.
In Raleigh, meanwhile, the legislature proposed a record 18 amendments to the North Carolina Constitution, including measures aimed at curbing the government’s power of eminent domain, an anti-union right-to-work provision and an expansion of concealed-carry gun laws. Colorado and North Carolina may represent the most striking examples of a national trend toward one-party control of state-level government. With Rhode Island Gov. Lincoln Chafee’s recent switch from independent to Democrat, 38 states have the governor’s office and the legislature controlled by the same party — the highest level in six decades.
While such one-party dominance is an almost surefire cure for gridlock, analysts say, it also points to the increasing balkanization of state governments as Democrats and Republicans move away from the political center. The concentrated power has sparked backlashes in Colorado and Minnesota on the left and Wisconsin and Michigan on the right.
“I think it’s part of a trend of party polarization that we’ve seen for the last decade or so,” said Seth Masket, a political science professor at the University of Denver. “The voters are increasingly being offered candidates who are either very liberal or conservative in elections, and there are far fewer of the moderates that we used to see win.”
As a result, he said, “You end up with more states with one-party control and when you see that, you get states that get things done.”
Indeed, state governments have shown little of the gridlock that has paralyzed the divided federal government, even on tricky budget issues. In Minnesota, Democrats — who regained control of the state in the November elections — passed a $2.1 billion tax increase at the behest of Gov. Mark Dayton targeting high-income earners, smokers and businesses.
The momentum on tax policy typically goes in the opposite direction in states where Republicans are in charge.
“Republican-led Indiana sliced income taxes and Alaska slashed oil taxes,” said a June 10 report in Stateline.org, which tracks trends at the state level. “Kansas is paying for an income tax cut by hiking sales taxes (the rate will still decline next year, but less than originally set), while competing proposals in North Carolina broaden sales taxes and lower the income tax.”
During the November elections, voters in 22 states elected legislatures with veto-proof majorities, meaning one party has the votes to override a gubernatorial veto. That override power was used to great effect this year in Arkansas, which elected a Republican legislature for the first time in 138 years.
Republicans used their newly elected majority to override the vetoes of Gov. Mike Beebe, a Democrat, on a slew of bills, including measures limiting abortions to the first 12 weeks of pregnancy and requiring voters to show photo identification at the polls.
One-party control doesn’t always guarantee political harmony. In Indiana, the Republican-controlled legislature this month overrode Gov. Mike Pence’s veto of a local income-tax measure, one of his three vetoes of bills from his own party.
Only five states — Iowa, Kentucky, New Hampshire, New York and Washington — have split legislatures. (Nebraska has a single, nonpartisan legislative chamber, although Republicans represent the clear majority there.)
“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.”