JEFFERSON CITY • A Republican mega donor and his family have poured another $2 million into their efforts to make Missouri a right-to-work state, pushing their political contributions this year past the $10 million mark.

On Monday, David Humphreys, president and CEO of Joplin-based Tamko Building Products, and his sister, Sarah Humphreys Atkins, contributed $1 million to Republican attorney general candidate Josh Hawley of Columbia. On Tuesday, Atkins wrote a $1 million check to a political action committee that has worked to oust lawmakers who oppose right-to-work laws.

The newest contributions put the Humphreys' financial stake in the 2016 election in the neighborhood of another Missouri mega donor, retired St. Louis investor Rex Sinquefield, who has dumped over $11 million into the 2016 election.

A Tamko spokesman said Humphreys was traveling and could not immediately be reached for comment.

A right-to-work law would ban contracts requiring workers to pay dues to a union. Supporters say the law would boost the state’s economy. Opponents say it would lead to lower wages and weaker labor unions.