Republican lawmakers are pushing the IRS, the Federal Trade Commission and the FBI to investigate the Clinton Foundation for potential criminal activity.

Led by Rep. Marsha Blackburn, R-Tenn., more than a half-dozen lawmakers have already signed onto a letter that is expected to generate much deeper interest before it is sent to the three enforcement agencies this week.

The letter, a copy of which was obtained by the Washington Examiner, highlights for IRS Commissioner John Koskinen a contradiction between the mission laid out in the original nonprofit filings of the foundation and the international and political activities it carries out today.

According to the letter, the Clinton Foundation applied for tax-exempt status in order to "construct a library, maintain a historical site with records, and engage in study and research." Those tax forms make no mention of the scope of work for which the Clinton Foundation is known today.

Blackburn led an unsuccessful effort last year to request an IRS investigation of the Clinton Foundation's status as a 501(c)(3) organization.

The letter also mentions Bill Clinton's position as an "honorary chancellor" for Laureate Education, a company that paid the former president $16.5 million for his services. Laureate donated up to $5 million to the Clinton Foundation, and a nonprofit group associated with the company's leadership later netted $55 million in grants from the U.S. Agency for International Development, an arm of the State Department.

"The foundation's activities cannot be ignored given the compelling public interest involved," said the letter, which is addressed to Koskinen, FBI Director James Comey and Edith Ramirez, chairwoman of the FTC.