HELENA (AP) -- A number of too-close-to-call legislative races left control of the state Legislature hanging in the balance -- leaving the possibility that both chambers will be close if not tied.

Returns in very tight races indicated modest gains by Republicans, bucking a national trend of Democratic gains.

Republicans and Democrats entered the election tied 50-50 in the House. All 100 seats were on the ballot.

Republicans hoped to crack into the Democrats' 27-23 advantage in the state Senate, where half of the seats were up for election, and appeared to do so.

In the Senate, the Democrats lost at least one seat and likely two, which could put the chamber at a 25-25 tie.

''It looks like a tie in the Senate,'' said Montana Democratic Party chairman Jim Farrell.

Republican Jim Peterson of Buffalo took the Senate seat formerly held by Democrat Jon Tester -- who successfully beat Conrad Burns in the U.S. Senate race.

And it appeared that the former Republican leader in the House, Roy Brown of Billings, was leading in his bid to move over to the state Senate seat previously held by Democrat Brent Cromley. But that race was still too close to call Wednesday.

But over in the House, races were even tighter. Three Republicans held leads of fewer than 20 votes each.

If those seats stay Republican, it appears the GOP could have a 50-49 advantage in that chamber with one seat going to the Constitution Party. The National Conference of State Legislatures said it would be the only legislative chamber nationwide to tilt in favor of the Republicans this election.

Constitution Party candidate Rick Jore of Ronan won his rematch against Democrat incumbent Jeanne Windham of Polson.

''We're happy with the seats we picked up in the Legislature,'' Republican party spokesman Brock Lowrance said. ''We look forward to the governor working with us and our friends across the aisle.''

But Farrell was challenging Republican Secretary of State Brad Johnson's handling of provisional ballots given to those who showed up to vote without proper identification.

The Democrat said Johnson blocked their attempts to get the names of those provisional voters who cast ballots in the tight House races. Democrats want to contact the voters and remind them to clear up the identification with election officials before the Wednesday deadline.

In the Senate, a high-profile Democrat switching chambers due to term limits won his race. Former House Democratic Leader Dave Wanzenried of Missoula, running for a Senate seat, beat Republican Rusty VanOverbeck and Libertarian Will Stock.

Gov. Brian Schweitzer campaigned hard for a number of legislative candidates on a platform that promised a property tax rebate and other initiatives.

Republicans fought back with promises of tax cuts of their own.

Both sides came away with noteworthy wins and losses.

Notable races:

- Brown's former Billings House seat was won by a Democrat, 26-year-old Kendall Van Dyk.

- A bitter contest in a House seat was too close to call, with Republican incumbent Scott Mendenhall of Clancy holding a 19-vote lead over Democrat Sheila Hogan of Clancy in a race that could be headed toward a recount.

- Republican incumbent Dee Brown of Hungry Horse lost to Douglas Cordier of Columbia Falls.

- Republican incumbent Karl Waitschies of Peerless lost to Julie French of Scobey.

- Democrat Bob Ebinger of Livingston knocked off GOP incumbent Pat Wagman.

- Republican Roger Koopman of Bozeman, an outspoken conservative, fought off a tough challenge from Democrat John Vincent of Gallatin Gateway.