Missouri voters approved Constitutional Amendment 2 with nearly 70 percent of voter support. The ballot measure is effective December 8, 2016.

The amendment establishes the Missouri Campaign Contribution Reform Initiative, reinstating campaign contribution limits for individuals or entities contributing to political parties, political committees, or committees to elect candidates for state or judicial office. The initiative also prohibits individuals and entities from intentionally concealing the source of such contributions, and bans direct corporation and labor union contributions to candidates.

State contribution limits, originally approved by voters in 1994, were repealed by the General Assembly in 2008. Constitutional Amendment 2 limits contributions to statewide candidates to $2,600 per election. Contributions to political parties are capped at $25,000 in the aggregate per election at the state, county, municipal, district, ward, and township levels combined.