The majority of Kentucky voters view Senate Minority Leader Mitch McConnell unfavorably and have deep concern about his support for unlimited campaign contributions, according to a poll released Wednesday by Public Campaign Action Fund, a group that seeks to limit the influence of big money on politics.

The statewide survey, conducted by Lake Research Partners, shows the Republican senator’s vulnerability on the issue of money in politics, one that his opponents plan to exploit in his upcoming reelection fight.

The poll of 5,000 registered voters in Kentucky, who were surveyed between Aug. 5 and Aug. 15, found that 52 percent had an unfavorable impression of McConnell. At the time, 46 percent said they would back his Democratic challenger, Alison Lundergan Grimes, while 40 percent said they would vote for McConnell and 14 percent were undecided. The poll has a margin of sampling error of 1.4 percentage points.

Voters were particularly receptive to the argument that McConnell backs increasing the role of big money in politics, with 53 percent saying they had “very serious doubts” about his support for allowing “wealthy CEOs, lobbyists and special interest PACS to give unlimited amounts of money to politicians, including himself.”

McConnell, a longtime foe of campaign finance restrictions, filed an amicus brief in May with the Supreme Court in the case of Shaun McCutcheon v. Federal Election Commission, arguing that federal limits on donations to candidates and parties should be rolled back. In late August, the court granted him permission to participate in the upcoming oral argument of the case, which challenges the current limits on how much individuals can give federal candidates and parties in aggregate in a two-year cycle.

Advocates of campaign finance reform plan to use that occasion to press their argument that McConnell is aligned with special interests, hoping to influence swing voters, particularly women.

Allison Moore, a McConnell spokeswoman, said Tuesday night that "there was widespread reports of push-polling in Kentucky during the time period that this poll was conducted and one look at these numbers confirms that something is amiss. There isn't a reputable pollster in the country that would consider this liberal advocacy poll anywhere near accurate."