Based on a January report from Texas Watchdog, a Houston public interest group has filed a complaint with the Texas Ethics Commission against one of the most powerful lobbying groups in Austin.

The complaint against HillCo Partners and the Mexican American Legislative Caucus was filed today by Texans for Ethics and Accountability and alleges HillCo violated the Texas Election Code by contributing to a legislative caucus during a prohibited time frame. State law bans contributions to lawmakers during the state legislative session.

Texas Watchdog reviewed  campaign finance forms and found the lobbying group had given thousands of dollars' worth of free office rent to MALC and its nonprofit foundation despite state laws that prohibit campaign contributions to lawmakers during the state legislative session.

The Texans for Ethics group takes issue in its complaint with the $31,762.50 HillCo gave to MALC's related foundation between January 2009 and June 2009. The group alleges that those donations fell within the prohibited period, which begins 30 days prior to a regular legislative session and ends 20 days afterward. The money appeared to be in exchange for rent in the building used by MALC.

Overall, the Texas Watchdog investigation found:

HillCo has given free rent to the caucus and its foundation for two years now; the foundation has valued the rent payments at about $5,000 a month, for an annual contribution of about $60,000. ...

On Feb. 6 of last year, the foundation sent a check for $5,041.66 to HillCo Partners for rent. Three days later, the foundation reported a contribution from HillCo Partners – for $5,041.66. The same thing happened each month from March through June, exact change passing in the mail, expenditure for rent duly noted, but the in-kind contribution box on the requisite finance reporting form was blank. The monthly contributions covered the duration of the legislature's regular session.

When contacted by Texas Watchdog, a HillCo partner defended the payments, but declined to answer questions concerning any benefits the firm may have reaped from the gift of free rent.

These donations raise questions about a serious conflict of interest: Can lobbyists funnel money to a group of lawmakers during the few months when they are crafting and voting on bills that could benefit, or harm, those same lobbyists?

Bill Miller says the rent his firm, HillCo Partners, provided to the all-Democratic caucus -- and to the Mexican American Legislative Leadership Foundation that shares the office -- is legal under state ethics rules. State law bans legislative caucuses from accepting "direct or indirect transfer of money, goods, services, or any other thing of value" from nonmembers during the legislative session, but the state Ethics Commission may have created a narrow loophole in 1994 allowing for contributions of free office rent in some cases.

The complaint comes a week after MALC chairman, state Rep. Trey Martinez Fischer, promised to answer questions about the relationship between his group and HillCo. Martinez Fischer so far has not returned several calls and e-mails to set up an interview.

The ethics and accountability group is headed by Justin Jordan, who has been active in Republican politics in Texas.