Democratic U.S. Rep. Jared Polis leads Republican state Treasurer Walker Stapleton by 7 percentage points in the state’s gubernatorial contest, according to the first publicly released poll of likely voters since this summer’s primary election.

Polis’ lead was especially strong with Colorado’s unaffiliated voters, women and those who make less than $75,000 a year, found the poll, which was jointly conducted by one Democratic-leaning firm and one Republican-leaning firm. Stapleton beats Polis with male voters and those who make more than $75,000 a year.

The live telephone survey of 600 likely voters was conducted by Keating Research and Magellan Strategies between Sept. 18 and Sept. 20. The results are weighted to reflect historic voter turnout during non-presidential election years. It was commissioned by Healthier Colorado, a nonpartisan health care advocacy organization.

While the poll gives Polis an edge, 47 percent to 40 percent, its margin of error is plus or minus 4 percentage points. Coupled with the 11 percent of voters who said they were undecided, the survey shows the race for the governor’s mansion is competitive.

Political observers have argued since the primary that Stapleton’s path to victory would be more difficult because of demographic trends favoring Democrats. One of the most striking data points is Polis’ lead among unaffiliated women: 48 percent said they were likely to vote for Polis, while 22 percent said they were inclined to vote for Stapleton.

The winner will succeed Gov. John Hickenlooper, a Democrat who is term limited.

The poll also asked participants about a variety of health care policy questions. Seventy-five percent of voters said they support an option for individuals with limited or expensive health insurance to purchase a state Medicaid plan. And 64 percent of those surveyed said the government should play a role in ensuring Coloradans have access to “quality and affordable” health care.

“We see a lot of division in politics today, but when it comes to health issues, Republicans, Democrats and unaffiliated voters in Colorado are uniquely united,” said Jake Williams, executive director of Healthier Colorado. “No matter who wins the race for governor or which party controls the Colorado House or Senate, Colorado voters of all political stripes clearly agree that we should make progress on health policy.”