Senator McCain's supporters have made much of his co-sponsorship of S. 190, an attempt to reform Fannie and Freddie during the 109th Congress. However, it may well be worth remembering that this was initially Senator Charles Hagel's bill, and secondly that its provisions met with significant opposition from conservative quarters. The real “maverick” in this tale certainly could be the Man Not Running, Senator Charles Hagel (R-NE). Neither have the other two co-sponsors assumed the Maverick Label – Senators Dole and Sununu.
Senator McCain signed on as co-sponsor of Hagel's Federal Housing Enterprise Regulatory Reform Act of 2005, urging its quick passage, [GovTrak] and this vocal support appears to be the totality of his exertions. S.190 promptly ran into controversies over policy differences between the House version (H.R. 1461, 109th) and the Senate edition in terms of housing requirements, portfolio limits, and program/product approval. [NAHB] From the National Association of Home Builder's perspective S. 190 had some serious flaws: “In contrast, (to the House version) the Senate bill, S. 190, contained many restrictive provisions that could harm the nation’s housing finance system, including: restrictions on asset holdings, discretion to raise minimum capital, burdensome program approval process, and a regulatory structure tilted away from housing. In addition, S. 190 did not require Fannie Mae and Freddie Mac to set aside monies to fund affordable housing initiatives, as provided in the House-passed bill.” [NAHB] S. 190 died quietly in the Republican controlled Senate Banking Committee at the end of the 109th Congress. The stronger of the two pieces of legislation, H.R. 1461, didn't draw rave reviews either.