The Republican nominee for Missouri secretary of state received a $250,000 donation from a St. Louis businessman who is pushing a statewide referendum to end income taxes in the state.

Acting state House Speaker Shane Schoeller (R-Willard) reported the quarter-million dollar donation from businessman Rex Sinquefield to the state Ethics Commission Friday. It is the second large-scale donation Schoeller has reported from Sinquefield; the first was a $150,000 donation during the Republican primary campaign in June.

The six-figure donations are legal in Missouri, which has not had campaign contribution limits since 2008.

Sinquefield's donations come as the businessman and philanthropist tries to get several referendums on the statewide ballot relating to the elimination of income taxes in the state. A referendum to eliminate the state income tax in favor of a 7 percent state sales tax referendum failed to make the ballot due to language in the analysis, although Sinquefield donated $1.2 million to help finance the effort.

Sinquefield's spokeswoman, Laura Slay, said that he was unavailable for comment, but described the businessman's general approach to contributions. "What I can tell you is that Mr. Sinquefield contributes to political candidates who share his commitment to education and tax policies that will improve educational and employment opportunities for every Missourian," she said in an email to HuffPost.

But his donation is raising eyebrows from Schoeller's Democratic opponent, state Rep. Jason Kander (D-Kansas City), who has made campaign finance limits and ethics reform his signature issues in the Legislature.

"Mr. Sinquefield is one of the regular customers of the secretary of state's office," Kander campaign manager Abe Rakov told HuffPost. "It raises red flags for a candidate to receive that donation."

Rakov described Sinquefield's total donations -- $400,000 -- to Schoeller as half of Schoeller's budget. Missouri candidates will present updated campaign finance reports to the ethics commission later this week. Schoeller reported less than $100,000 in his campaign account following the Aug. 4 primary. Schoeller also reported donations of 10,000 from the Missouri Soybean Association and $10,000 from SRC Holding Corp. since the primary.

The secretary of state's office controls the petition process for referendums, along with the wording of the referendums on the ballot. Both issues have received attention during the current election cycle, with Republican accusing outgoing Secretary of State Robin Carnahan (D) of wording referendums to favor her political position.

Sinquefield has made several other large donations in recent days, according to the Kansas City Star. Among these: $600,000 to A Safer Missouri, which is pushing a statewide referendum for local control of the St. Louis police department; and $160,000 to the Missouri Club for Growth. He gave the Club for Growth $500,000 in June. Since 2008, Sinquefield has donated $200,000 to former state House Speaker Steve Tilley, who briefly sought the GOP lieutenant governor nomination late last year; $130,000 to St. Louis County Executive Charlie Dooley, $75,000 to St. Louis Mayor Francis Slay and $30,000 to St. Louis Board of Alderman President Louis Reed.

Sinquefield also donated $385,000 to state Sen. Brad Lager (R-Maryville) who lost last month's GOP primary for lieutenant governor. Sinquefield was one of five donors to contribute a total of $1.5 million to Lager's unsuccessful campaign, including $900,000 from the family of Joplin businessman David Humphreys.

Campaign finance has played a role in the secretary of state's race since the GOP primary when state Sen. Bill Stouffer (R-Napton) received over $117,000 in free billboard advertising through a campaign coordinated by the state's billboard industry. The spokesman for the Missouri Outdoor Advertising Association told HuffPost at the time that the donations were to reward Stouffer for his work on behalf of the billboard industry in the Senate. The association indicated that it was also considering backing Schoeller as well.

Rakov indicated that Kander has raised $900,000 for his campaign with the money coming from 1300 donors. He said that the Democrat would continue a grassroots campaign.

"We'll keep doing what we're doing," he said. "We are talking to supporters across the state."