Two campaign-finance watchdog groups have asked the Internal Revenue Service to investigate a nonprofit advocacy group affiliated with the Republican political adviser Karl Rove, writes The New York Times.

In a letter released Tuesday, leaders of the watchdog groups—Campaign Legal Center and Democracy 21—say that Crossroads Grassroots Policy Strategies, or Crossroads GPS, “was organized to participate and intervene in the 2010 Congressional races,” in violation of its status as an advocacy group under Section 501(c)(4) of the Internal Revenue Code.

A Democratic senator last week sought an IRS review of advocacy groups, which have become increasingly active during this year’s campaign, primarily on behalf of Republicans. Such organizations are not required to disclose their donors as long as their “primary purpose” is not political.

Steven Law, chief executive officer of Crossroads GPS, told the newspaper that his organization is advocating on “a suite of issues that are likely to see some sort of legislative response” and not on influencing the November elections in a partisan way.

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