DENVER — Republicans posted sweeping gains in state houses across the nation on Tuesday, taking control of the most state legislatures in nearly 100 years and approaching a record number of governors’ seats — a critical development at a time when most major policy has been coming out of states, rather than Washington.
With final tallies still being compiled, the Republicans now control both houses of the legislatures of 29 states, the highest number since 1920. By contrast, Democrats now control both chambers in just 11 states. The Republicans netted at least two governor’s seats — while holding off strong challenges from Democrats in places like Wisconsin and Florida — leaving the party with at least 31 governorships, the highest since 1998.
“It was a worst-case scenario for the Democrats,” said Tim Storey, an elections analyst at the National Conference of State Legislatures. “Republican voters turned out better, were more enthusiastic, they just swamped the Democrats. The anti-Obama mood was too strong even for many Democratic candidates who were well funded and had run equally active campaigns. In the state legislatures, the Democrats were overwhelmed by the environment.”
With the states acting as laboratories for legislation that cannot advance in Washington, policy changes are likely on a variety of issues. “What they’re going to do now is move forward a Republican set of policies — lower taxes and a focus on job creation,” Mr. Storey said. “It will be much harder to see expansions of Medicaid. And there may be fewer restrictions for gun owners.”
The results suggested a backlash by voters to what had been a record-high number of states under the full control of a single party, at least when it came to Democrats. Going into the election, Democrats held both houses of the Legislature and the governor’s seat in 13 states; that number has been reduced to seven, though a few legislative races are still being tallied.
"The voters have asked for divided government,” said Bruce Rauner, the Republican governor-elect in Illinois — Mr. Obama’s home state, where Democrats had held sole control of the state capital for more than a decade. “For the first time in many years, we’ll have a Republican governor and a Democratic legislature.”
In Minnesota, Gov. Mark Dayton, a Democrat, was re-elected, but Republicans took control of the state House, ending the Democrats’ two years of full control of the state capital. “I think what we probably learned is that Minnesotans believe that the Democrats overreached in the last two years — on taxes, on spending, and in other areas,” said Kurt Daudt, who had been the Republicans’ minority leader in the House.
Republicans lost the governor’s seat in Pennsylvania, a state that had been under single-party control before Tuesday. But they put two more states under their single-party rule. Republicans seized both houses in Nevada, the home state of Senator Harry Reid, the Senate Democratic leader, and a place that Democrats have viewed as moving in their direction. Brian Sandoval, the Republican governor, was easily re-elected. They also won the governorship in Arkansas, putting that state into the single-party control category.
Republicans will go into next year holding full party control in at least 23 states, the same as this year, though they could end up with 24, depending on whether they continue holding Alaska, where votes were still being tallied in the governor’s race. A rare bright spot for Democrats on an otherwise bleak night was that they kept Republicans from taking over chambers in Kentucky and Iowa.
Republicans hailed the results as evidence of public support of an agenda, played out in states like Wisconsin, that included scaling back union pension plans and the political power of unions and trying to combat President Obama’s health care plan.
“Obamacare was a big driver in many of these races,” said Phil Cox, the executive director of the Republican Governors Association. “And that’s certainly going to be on the table.”
On Tuesday afternoon, Pat Hickey, who has been the Republican minority leader in the Nevada Assembly, said his party now had “a historic opportunity as well as challenge to be able to implement some of the reforms and remedies that we’ve argued for many sessions, if not decades.”
Mr. Hickey said the newly Republican-held capital might tackle education issues and a restructuring of the state tax system, as well as examine collective bargaining rules and pensions. “All of these things will be on the table,” he said.
In Minnesota, where Republicans took control of the state House, Paul Thissen, a Democrat who will no longer be speaker, said he expected the change would stall hopes Democrats had for the coming year, including the possibility of more spending on transportation and efforts to expand worker protections like paid parental leave.
In another measure of the shift in power, Republicans are poised to control 67 to 69 legislative chambers, up from 59 before the election, according to officials in both parties.
Matthew Walters, the president of the Republican State Leadership Committee, said that the historic high for legislative seats held by Republicans was 4,001 in 1928, and that the high for chambers controlled was 64 in 1920. “We are confident that once all the final recounts are done, that we will be at a new all-time Republican high for chambers and a new all-time high of Republican seats in state legislatures,” he said.
The showing in some ways echoed the Republican victories in the last midterm elections in 2010, when Republicans also made significant gains in state houses. But Michael Sargeant, the executive director of the Democratic Legislative Campaign Committee, a group that tries to elect Democrats to state legislatures, said he was confident that the party would pick up many of the seats it lost in the 2016 presidential election, which is what happened in 2012.
“Don’t take this as if we were joyous,” he said. “We are not at all. But we thought this could have been worse. We held the Iowa Senate. We held the Maine House. Those were big targets for Republicans.”
In one sense, the Republican victories in state houses may prove to be less consequential than the ones of 2010; those legislatures were the ones that drew district lines as part of the nation’s reapportionment process, giving the party what has proved to be a big advantage in Congressional and some statehouse races that could last through 2020.