A statement from McMillin says he wants to focus his attention on "making my family's world a better place."
The House's efforts will include charitable donations, weekly education and awareness efforts and potential legislative action.
Rep. Kreg Battles, D-Vincennes, was recently nominated for a fifth term in this month's primary.
The approved legislation releases $200 million right away but requires state budget committee approval for the second $200 million.
The Indiana House Ways and Means Committee passed a bill Thursday that proponents say will increase quality of elder care in the state.
Indiana House Republicans are losing Representative Bill Davis. Davis is taking a new job with Office of Community and Rural Affairs.
The budget contains increased K-12 education funding, permanent infrastructure funding, and pays down some of the state’s debt.
House Speaker Brian Bosma will announce new leadership for the Ways and Means committee this week.
Scott Pelath (D-Michigan City) will lead the 31 member Democrat minority in the state House of Representatives.
Republicans won 69 seats in Indiana's House of Representatives during this week's election.