JEFFERSON CITY, Mo. -- Democratic Attorney General Jay Nixon is calling for stricter campaign contribution limits on political parties as he ramps up his challenge to Republican Gov. Matt Blunt.

Political party committees currently can give candidates up to 20 times the amount of contributions as individual donors, business or interest groups -- an exception Nixon derided as a "significant loophole." He proposed to cap party contributions at the same amount as everyone else can give.

"There's no good reason that political committees should have more power than regular Missourians in their contributions," Nixon said Tuesday during a conference call hosted by his gubernatorial campaign.

Under current Missouri law, statewide candidates such as Blunt and Nixon can receive up to $1,275 per election from most donors -- an amount due to be adjusted for inflation next week. But they can take $12,750 in cash plus $12,750 of in-kind contributions from political party committees.

Wealthy individuals and businesses sometimes get around their own limits by giving larger amounts to various local party committees, which then pass on the money to candidates. The Missouri Ethics Commission essentially upheld the practice in a 2001 decision.

At the end of 2000, there were 176 political party committees registered with the state Ethics Commission. That now has nearly doubled to 346, said Joe Carroll, the commission's campaign finance director.

In 2006, legislators passed a measure that supporters claimed would make it easier for the public to follow campaign money by eliminating the need to funnel it through party committees. The law repealed individual contribution limits, effective in January 2007. It also banned cash contributions by political parties to candidates, but let parties make unlimited amounts of in-kind contributions such as campaign signs and pamphlets.

Nixon urged Blunt to veto the bill. But Blunt praised it as reform and signed it into law.

Once the limits were lifted, Blunt, Nixon and other candidates started collecting large charges. But the Missouri Supreme Court re-imposed contribution limits last July, striking down the repeal because lawmakers had linked it to another provision found unconstitutional by a trial judge.

The ruling wiped out a large portion of the cash advantage Blunt had accumulated over Nixon. Blunt is refunding nearly $4.5 million in contributions that exceed the retroactively reimposed limits; Nixon is refunding more than $1.3 million.

Blunt still believes that repealing contribution limits makes it easier for the public to track campaign money, spokesman Rich Chrismer said. But lowering the limits for party contributions also could accomplish that, he said.

"The governor is interested in any reform that would increase transparency," Chrismer said.

Senate Majority Leader Charlie Shields and House Majority Leader Steven Tilley, R-Perryville, both said they will support legislation this year repealing contribution limits.

"I think anytime you have limits you're going to have people trying to figure out how to get around them," said Shields, R-St. Joseph.

Nixon said his proposal would be sponsored by House Minority Leader Paul LeVota, D-Independence. In an earlier interview with The Associated Press, LeVota talked of going even further and simply prohibiting party contributions to candidates.

Repealing state contribution limits, as favored by Republican leaders, would run contrary to the spirit of a federal law limiting contributions to presidential candidates at $4,600, LeVota said.

"It doesn't make sense to say you can give more to a state representative candidate than you can to a candidate for president of the United States," he said.