JEFFERSON CITY, Mo. -- Nearly half the seats in the Missouri Legislature up for election this year already have essentially been decided through the primary election.

Voters cast ballots for all 163 members in the state House and half of the 34-member state Senate on Tuesday. In many of those races, the only competition was between members of the same political party. Others will face only a Libertarian or Constitution party challenger in the fall election.

Of the 17 Senate seats up for election, three Republicans face no opponent in November and two others face either a Libertarian or Constitution party member. Two Democrats also wrapped up their campaigns by winning primaries and another must beat a Libertarian.

Sen. Brad Lager, a Republican from Savannah, had no challenger in the primary and is uncontested in the general election. House Speaker Ron Richard also was unchallenged in his bid for a Senate district representing Joplin.

Two others won four-way party primaries and face no opponent in November. Republican Mike Kehoe won his primary for a Jefferson City-area district. Democrat Maria Chappelle-Nadal, a state House member, won her contest for a St. Louis-area seat.

In the state House, 42 Republicans and 28 Democrats either will face no opponent or only a third-party challenger in November. It takes 82 members to the control the chamber, which Republicans have led since 2003.

Voters knocked off three current House members in their primaries.

Complete but unofficial election results showed that St. Louis Democrats James Morris and Hope Whitehead lost their re-election bids. Morris was elected in 2008 and was defeated by Penny Hubbard, whose son held the seat before Morris.

Whitehead took office in February to replace Democrat Talibden El-Amin, who resigned after pleading guilty to a federal bribery charge. She was defeated by Democrat Karla May.

No Republican has filed to run in either House district.

In southwestern Missouri, Republican Nita Jane Ayres finished third in a three-way Republican primary for a district in Stone and Taney counties. Ayres took office in February after Republican Dennis Wood resigned to accept an appointment to be a county commissioner.

Don Phillips, a retired trooper for the Missouri State Highway Patrol, won that Republican primary and does not have an opponent in the general election.