Gov. Kathy Hochul has expanded her commanding lead over Representative Lee Zeldin, her Republican challenger in the New York race for governor, according to a Siena College poll released on Wednesday that showed her leading by 17 percentage points.
The poll suggested that Ms. Hochul, a Democrat from Buffalo vying for her first full term, has improved her standing among voters since a Siena College survey in August that had her up by 14 points.
With six weeks until Election Day, Ms. Hochul has held a comfortable lead in most public polls, buoyed by a seemingly insurmountable fund-raising edge that has allowed her to spend freely on television ads attacking Mr. Zeldin over the past few weeks.
The poll was but the latest indication of the uphill battle that Mr. Zeldin faces to capture the governor’s office in New York, where Democratic voters outnumber Republicans two to one. The state hasn’t elected a Republican governor since George E. Pataki, who left office in 2006.
Notably, Ms. Hochul made significant gains in the New York City suburbs: She was beating Mr. Zeldin by five percentage points in the poll, which was conducted last week, compared with the August poll, which had her trailing Mr. Zeldin by three points in the suburbs.
Ms. Hochul also modestly improved her favorability rating among Republicans, while Mr. Zeldin lost some support among his party’s voters, with 77 percent of Republicans saying they would vote for him, down from 84 percent in August. Even so, Mr. Zeldin continued to hold a slim lead among independent voters and is virtually tied with Ms. Hochul in upstate New York, according to the poll, which surveyed 655 likely voters.
The poll found Ms. Hochul holds a commanding lead in vote-rich New York City, with Mr. Zeldin well short of the 30 percent of votes he has said he will need to win.
Mr. Zeldin, an ally of former President Donald J. Trump who has represented Suffolk County in Congress since 2015, would have to make significant inroads among independent and suburban voters in the final weeks of the campaign to overcome Ms. Hochul’s strong support in New York City and among women, Latino and Black voters.
Ms. Hochul began spending heavily on television and digital advertisements in early September, many of them trying to define Mr. Zeldin as “extreme and dangerous” based on his view on abortion and his votes on Jan. 6 to overturn election results in key states. By the end of the week, her campaign will have spent roughly $7 million on the ads, according to AdImpact, a media tracking firm.
Mr. Zeldin, who has struggled to replenish his campaign reserves after a costly primary, had spent just under $1 million during the same period, the firm has found. Ronald S. Lauder, the conservative cosmetics heir, has funneled more than $3 million into a pair of pro-Zeldin super PACs to try to narrow the gap, but the bulk of the groups’ ad buys attacking the governor as being soft on crime only began airing in recent days.
While Mr. Zeldin has sought to amplify a handful of Republican-friendly polls showing the race as far tighter, the high-dollar donors who could reverse his financial fortunes could conclude that victory is simply slipping out of reach and put away their checkbooks, leaving him unable to defend himself from Ms. Hochul’s onslaught.
The poll, which had a margin of error of 3.9 percentage points, found that other top Democrats running statewide — Senator Chuck Schumer; Thomas DiNapoli, the state comptroller; and Letitia James, the state attorney general — were also dominating their Republican opponents in their races.