How are Democrats, Republicans doing in governor's races?

Like most midterms, the 2014 congressional races are widely seen as a referendum on the president, even though his name doesn't actually appear on any congressional ballots. With all the focus on the Senate it's sometimes easy to forget that at the state level, most of America is governed by a Republican administration: the GOP holds 29 of 50 governor seats, covering more than half the population -- so with 22 of them up, this November can also be seen as something of a referendum on Republican executives, too.

And as with the House and Senate races, Republicans appear to have an edge overall. Most of their gubernatorial incumbents are ahead or even in our latest round of our CBS News/New York Times/YouGov Battleground Tracker state estimates. That includes a number of spotlight governor's races taking place in "blue" and battleground states - and come 2016 it will not surprise if a few of these Republicans eye the White House themselves, touting an ability to win in Democratic territory.

But a number of tight contests are in the spotlight: in Wisconsin Scott Walker is up slightly over challenger Mary Burke 49 percent to 45 percent in our estimates. One might not expect anything different in this closely-divided state, where Walker had to face down a recall vote early in his tenure. Walker was one of many GOP governors who swept into office in the 2010 wave and enacted a number of conservative - and to many, controversial - reforms.

In Florida, it's a contest between a Republican and former Republican, as incumbent Rick Scott has 46 percent to 43 percent for Democrat Charlie Crist, within the margin of error. Maine offers another tight contest between incumbent Republican Paul LePage and Democrat Mike Michaud, separated by a single point in the estimate. Colorado cements its place as one of the hottest action spots of the 2014 season, as incumbent Gov. John Hickenlooper - once considered to have an easy road to re-election - finds himself locked in a tossup race with Bob Beauprez. Hickenlooper (like Senate Democrat Mark Udall) benefits from a large double-digit gender gap to keep things close.

And in Kansas, incumbent Gov. Sam Brownback maintains a lead in his re-election race, but finds himself in a competitive race after losing the support of a number of prominent members of his own party and following the state's budget shortfall. Among voters in our estimates, Brownback has the backing of seven in ten Republicans but is even with Democrat Paul Davis among independents.

The current matchups in Alaska and Rhode Island were not tested in this round of surveys.

Meanwhile we see many Republican governors favored for re-election in states that could be Presidential battlegrounds or blue next cycle, such as in Brian Sandoval in Nevada, Susana Martinez in New Mexico, and John Kasich in Ohio, for instance. They don't draw overwhelming numbers of Democrats (at best in low double-digits) but do extremely well among independents in these studies.

In a era marked by sharp partisan divides for federal offices, governor's races by definition can turn more on local, specific issues that don't always hew to the national party lines, making for more idiosyncratic races and sometimes more accountability - for better or worse - for the elected officials.

How it works

Data in the second wave of the New York Times/CBS News Battleground Tracker are based on online interviews with 108,725 voters conducted August 18-September 2, 2014, in all 50 states and 435 congressional districts across the United States.

YouGov, of Palo Alto, Ca., assembled the panel of registered voters, and conducted the selection, interviewing and tabulation. All 107,623 respondents in the first wave were recontacted and 68,974 were re-interviewed for this wave. In addition, 39,751 new panelists were added for the second wave. All panelists have previously opted-in to a YouGov or other online survey panel.

In each state and district, respondents were selected to match the demographics of registered voters. In 66 competitive House districts and the 15 smallest states with Senate elections this year, YouGov interviewed disproportionate numbers of voters to increase the sample size for these races.

Respondents were matched and then weighted to demographics from the 2010 U.S. Census Congressional District Summary File (age, sex, race and Hispanic origin), the 2012 American Community Survey (education, marital status, employment status, home ownership and citizenship), and the Current Population Survey November 2012 Registration and Voting Supplement (voter registration and turnout). Past voting information is based on the 2012 National Election Pool Exit Poll and 2012 election returns.

To build the model, we have quite a bit of information about the people that are not in our sample and the races in those districts. From the Census, we know their demographics. From the 2012 election returns, we know the proportion who voted for each candidate in 2012 (or didn't vote). From the 2012 exit poll, we know the relationship between voter demographics and 2012 vote. And from out 2014 panel, we have data on how these variables relate to 2014 voting intentions.

We have combined these data into a statistical model that predicts 2014 vote on the basis of demographics and past vote. The model uses common patterns in the data to make estimates for people not interviewed. For example, if most of the 18-24 year old white female respondents in the sample who voted for Republican presidential nominee Mitt Romney in 2012 tell us that they intend to vote for the Republican congressional candidate in 2014, the model then predicts similar behavior for 18-24 year old white female voters in a district where our sample doesn't include any voters of this type. Where we have a few voters in a particular group, we average the model predictions with the sample, with the model estimates discounted as the sample size in that group increases. These techniques have been developed by statisticians and are commonly used for small area estimates by the Census.

The Battleground Tracker uses a different methodology from that of the regularCBS News Poll. The CBS News Poll is conducted using RDD sampling and telephone interviews.

The reported "margin of error" is an estimate, based upon a statistical model of the variability that would result theoretically from repeated applications of the same procedures. The practical difficulties of conducting any measure of public opinion may introduce other sources of error. More information about the methodology and state by state data is available at the yougov.com website.