Missouri Auditor Tom Schweich says an audit released Monday shows that Gov. Jay Nixon violated Missouri's constitution when he withheld money from two recent state budgets.

Schweich says the governor had no legal right to withhold $172 million from several state programs to help cover costs from the Joplin tornado and other recent natural disasters during fiscal year 2012.

"Under Article 4, Section 27, of the Missouri Constitution, the governor may only withhold money if it's been appropriated and signed into law, (and) if actual revenues are coming in below estimates, because you would be short (of) money, it makes sense," Schweich said  "But when actual revenues are above estimates, the constitution very clearly precludes the governor from withholding money."

Schweich added, "It looks like it was more of a political tool than a budgetary tool."

The audit report also contains an official response from the governor's office, which disputes Schweich's conclusion. Nixon's office says that the governor did follow the law when he withheld money from the state budget. Nixon officials also said that the audit contains inaccurate information but added that Schweich is "entitled to his opinion."

The audit was released two days before the scheduled start of this year's veto session, during which the GOP-controlled legislature will consider overriding several of the governor's vetoes made earlier this year.

Schweich sued Nixon three years ago over those withholds, but the case was tossed out by the Missouri Supreme Court. Another lawsuit is possible, though Schweich won't tip his hand yet. He did indicate that another lawsuit could hinge on whether voters approve a constitutional amendment to limit the governor's ability to withhold funding from the state budget.

"We'll look at all the other things going on, we'll look at how the ballot initiative goes, we'll get a sense from the public on how they feel about it, and then we'll make a decision at that point," Schweich said.

The full audit, along with the response from the governor's office, can be found here.

Follow Marshall Griffin on Twitter:  @MarshallGReport

Send questions and comments about this story to feedback@stlpublicradio.org.