Ballotpedia’s Geoff Palay and Leslie Graves report on the expected Republican gains:

Republicans will make significant gains in state legislatures on November 2nd, according to our election projections.

The Republican Party is poised to gain control of up to 18 state legislative chambers on election night. Going into the elections,Democrats control 28 state senates while Republicans control 20. We project that Republicans will gain control of the Alaska andIowa senates. Meanwhile, Alabama, Maine, New Hampshire, New York, North Carolina and Wisconsinare still too close call and remain a toss-up.

Additionally, the GOP is poised to pick-up at least five state houses and could win as many as 10 houses on election night. Democrats currently control 32 state houses to the GOP’s 16. We project that the GOP will win a majority in Indiana, Montana, Ohio,Pennsylvaniaand Wisconsin. In addition, Democratic-controlled houses in Alabama, Colorado, North Carolina, New Hampshire andIowa rest in the toss-up category.

Of the 99 state legislative chambers in the United States, 88 are holding state legislative elections on November 2, 2010. 1,167 of the country’s 1,971 state senate seats are up for re-election, while 4,958 (91.6%) of the country’s 5,413 state house seats are up for re-election. Altogether, 6,125 of the country’s 7,384 state legislative seats are up for re-election in this volatile election year. Democrats control the majority in 52 of the chambers that are up for re-election while Republicans are the majority in 33.