Three prominent Missouri Republican donors are pouring big money into the campaign supporting embattled Wisconsin Gov. Scott Walker.

The three are Stanley M. Herzog of St. Joseph-based Herzog Contracting, David C. Humphreys and his sister Sarah Atkins, both of Tamko Building Products in Joplin. Each donated $250,000 to help Walker fight a recall effort later this spring.

Their combined $750,000 represent more than one fourth of the $2.39 million that Walker has reported raising.

Atkins donated on Jan. 13, with her brother following suit on Jan. 14, and Herzog on Jan. 17.

The Humphreys family has been among Missouri’s top GOP donors for years. David Humphreys had been the biggest donor to Lt. Gov. Peter Kinder, a Republican who had been expected to run for governor this fall until controversy broke over his acquaintance with a former stripper and his acknowledgement that he used to frequent the East Side strip club where she worked in the 1990s.

Humphreys demanded his donations to Kinder be returned and called for Kinder to drop his candidacy — and resign his current office. Kinder kept Humphreys’ money and his office but did drop his gubernatorial bid. Humphreys now has donated to the Lieutenant Governor campaign of Sen. Brad Lager, R-Savannah, Kinder’s GOP rival.

Labor groups and teachers have collected one million signatures in Wisconsin in an effort to recall Walker, a Republican who pushed through some tough austerity measures last year, including some that limited public union bargaining rights.