She has been an activist -- critics say overly active -- attorney general during her two terms. In addition to beefing up the office's violent crime unit and enforcing the death penalty, she has aggressively pursued consumer fraud cases and predatory lenders. She opposed the federal Patriot Act and joined a lawsuit against the Bush administration over global warming, which the U.S. Supreme Court has agreed to consider.
But Republicans hope this year's spate of local scandals not only tarnishes her crime-fighting credentials, but also thwarts any attempt to use the Washington corruption theme against Wilson.
The most prominent scandal involves former state Treasurer Robert Vigil, a Democrat, who is charged with accepting kickbacks. During his trial, a former state watchdog testified that a letter was prepared that urged Madrid to look at one of the outside investment advisors implicated in the case. But Madrid's office said it never got the letter, and it was unclear whether it had been sent.
Vigil's federal trial ended in a hung jury. A retrial is set for Sept. 5. Meanwhile, Madrid has filed state criminal charges against four of those implicated in the Vigil case, saying she believed they were getting off too easily in a deal with federal prosecutors.
The Albuquerque Journal, in a stinging editorial, accused Madrid of jeopardizing the federal case in an effort to boost her congressional bid. "My office is run in a nonpartisan way and always has been," she responded, waving off the accusation.
Democrats who recruited Madrid are unfazed by the controversy. "She's the best possible candidate for that seat, absolutely," said Bill Burton, a spokesman for the Democratic Congressional Campaign Committee, whose boss, Rep. Rahm Emanuel of Illinois, called Madrid as many as a dozen times and sent along a cheesecake to sweeten the courtship.
Madrid is a personable campaigner, striding into a room with brio, although at 5 feet, she is almost always the shortest person there. She also is tough, with an ability to take an accusation, twist it, then volley it back.
Madrid will need all her dexterity when she shares a stage with Wilson. The congresswoman is a Rhodes scholar and skilled debater, who has survived several tough campaigns.
"How the candidates look and project themselves" could well decide the race, said Christine Sierra, a University of New Mexico political scientist.
Madrid hopes for several debates; Wilson, so far, is uncommitted.