Missourians for Health Care Freedom, the chief campaign group for Proposition C, launched a statewide radio ad campaign today that will continue until the statewide vote Aug. 3.

The initial ad buy totals $25,000 and will increase if more money comes in, said campaign manager Patrick Tuohey. The ads began airing in west Missouri and should be heard in the St. Louis area by Tuesday, he said.

Proposition C seeks to block some of the federal mandates in the new health-care law, particularly the 2014 requirement that most people buy insurance or face tax penalties.

Although critics say that Prop C can't trump federal law, both sides agree that one of the measure's aims -- if it passes -- is to put political pressure on Washington supporters of the federal health-care changes.

So far, no organized effort has emerged to oppose Proposition C, which is supported heavily by Republicans and conservatives.

Missourians for Health Care Freedom's last and latest campaign finance report, filed today, shows the group has raised $74,848.07 -- most of it since July 1.

The latest donors include several well-known St. Louis area Republican conservatives, including Mark Andrews ($10,000) and Fred Sauer ($5,000).

Other than the ad buys, the bulk of the group's spending is for Tuohey's services. The report showed that $14,192 was paid to Market & Communications Research, a Kansas City-based firm founded by Tuohey in 1999.