Andrew Harrer / Bloomberg Iowa attorney general Tom Miller.

Iowa’s Democratic Attorney General Tom Miller is known for taking on big business. Elected to eight four-year terms, he led a multi-state anti-trust case against Microsoft in 2001 and filed a suit against 79 drug companies in 2007, alleging they illegally profited by inflating prices for drugs purchased through Medicaid.

Most recently, Miller took the lead on the investigation by all 50 state attorneys general into the “robo-signing” foreclosure scandal, where several big banks allegedly approved taking away people’s homes without adequately verifying the facts in court, as required by law in some states.

Last fall, just after he made the announcement that he would look into the foreclosure mess, contributions to Miller’s campaign coffers for November’s election soared, thanks in large part to out-of-state lawyers who make a living representing big banks, a new report from the National Institute for Money in State Politics finds. “Nearly half of the money Miller raised in 2010,” NIMSP reports, “was donated after the October 13 announcement that he would be coordinating the 50-state attorneys general investigation.”

Two Miller contributors have become directly involved in defending the banks in the probe. One, Meyer Koplow of Wachtell Lipton in New York, gave Miller $5,000 and is representing Bank of America in direct negotiations with Miller, the attorney general tells TIME. Another, Elizabeth McCaul of Promontory Financial Group, gave Miller $10,000 and is consulting Bank of America in the negotiations, Miller says. Bank of America was one of the first and most prominent institutions accused in the foreclosure investigation. It gave more than $80,000 to the Democratic Attorney Generals Association, which spent more than $200,000 on Miller’s campaign, Miller says.

Miller says Kaplow and McCaul are old friends and professional associates, and that they were not working for Bank of America before election day. He says neither has discussed the campaign contributions with him since they began work for the bank.

The NIMSP report and revelations of campaign contributions by those working for Bank of America come at a sensitive moment, as Miller is in the thick of far-reaching negotiations with the banks. Though the case started as an investigation into robo-signing, it has broadened. The talks are aimed at a settlement that could set the terms by which banks service current and future home loans, and determine how they foreclose on properties. That could complement, or supercede, a settlement between banks and federal regulators reached earlier this year.

Talks over monetary aspects of a potential settlement between the AGs and the banks are just getting under way. New rules for banks writing down mortgage principal and the establishment of a bank-paid fund to help with loan modification are on the table. Some reports have potential bank payments reaching $20 billion but sources on both sides suggest that number is high. The breadth of the negotiations has caused seven Republican attorneys general to split with the 43 other AGs.

In early March, American Banker published a 27-page term sheet that Miller and the other attorneys general had presented to the banks in the talks. “We’ve had negotiations and have agreement on some of the terms but no overall agreement,” Miller says.

Miller objects strongly to the NIMSP report. “It is extremely false and misleading,” Miller says. He disputes the report’s assertion that many of his campaign contributors have a “vested interest in the final terms of the settlement.” Other than Koplow and McCaul, none of the other lawyers named as campaign contributors in the report are involved in the case and none has an interest in the settlement, Miller says.

Miller also says the report commits “an omission of material fact” in its description of his fundraising by comparing 2010 fundraising to prior races. “This race was unlike any race I’d been in before,” Miller says. “It was a race where the other side had $2.2 million. The most any of us ever spent in this race before was $300,000 or $350,000,” he says. Miller says he didn’t have a competitor in 2006 and that in 2010 he and his supporters eventually raised and spent around $1 million.

Kevin McNellis, the author of the report, says the fact that he compared 2010 to 2006 without mentioning that there was no competitor in that race was “an oversight on my part.” Though the report argues that the campaign contributors’ interest in the outcome of the settlement of the foreclosure investigation is “vested,” which means “guaranteed” or “unconditional,” McNellis says he does not know which individuals or firms are directly involved in negotiations.

But McNellis asserts that, “When they were contributing last fall, I’m sure that it was something they were very keenly aware of, that Miller was leading the investigation.” They would have an interest in the outcome, McNellis says, “even if they weren’t directly involved in the negotiations.”

Neither McCaul nor Koplow would comment for this story.

–with reporting by Melissa August