Donald Trump, who had been gaining on Hillary Clinton in a series of Colorado voter surveys for almost a month, suffered a setback in a new opinion poll on the presidential race — the first major survey to be conducted in the state since the candidates’ Sept. 26 debate.

The Monmouth University Poll, released Monday, shows Democrat Clinton leading Republican Trump among likely voters in the state by 11 percentage points in a four-way contest, 49 percent to 38 percent.

The Colorado survey, conducted Sept. 29 through Sunday, shows Libertarian Gary Johnson supported by 7 percent of those surveyed and Green Party candidate Jill Stein by 3 percent.

According to polls averaged by Real Clear Politics, that’s the biggest lead for Clinton in Colorado since an NBC-Wall Street Journal-Marist College in early August showed the former U.S. senator from New York and secretary of state with a 12-point advantage here in a matchup of Clinton, Trump, Johnson and Stein.

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