Undated (AP) _ Democrats hailed their prospects for winning the redistricting battles that will follow the 1990 census as legislative election results showed they maintained control over two-thirds of the nation's state Houses and Senates.

Although Republicans said they believed they had won 16 to 30 state legislative seats from Democrats, figures available Wednesday indicated the GOP suffered a net loss of control in one legislative chambers and fell from a tie in a second.

Control of the legislatures is critical to the national political scene because state lawmakers will redraw congressional boundaries in 1991 to account for the population shifts reported in the 1990 census.

Skillful redrawing of the district lines can allow a party to win more seats in Congress by protecting its own turf while dividing and conquering strongholds of the other party.

''This is a terrible blow to the Republicans in terms of their attempts to take over the legislatures to exert political control over redistricting,'' said Timothy Dickson, executive director of the Democratic State Legislative Leaders Association.

The Democrats' hand is likely to get stronger in 1990 if they win more state seats that year, which the party that loses the White House usually does in off-year elections. That spells trouble for the Republicans.

''We would obviously have liked to pick up some more,'' said Molly Gaylord, a field director for the Republican National Committee. She said she hoped for a strong showing in 1990.

Democrats made a net gain of control of one state Senate and Republicans had a net loss of control of one state House, according to figures compiled by The Associated Press and the National Conference of State Legislatures.

Democrats lost 10 chambers in 1980 and seven chambers in 1984, although they won back some of them in the off-year elections of 1982 and 1986.

The elections left Democrats in control of 32 state Senates and 36 state Houses, while Republicans controlled 16 Senates and 12 Houses. In some other state bodies, power was evenly split. Nebraska has a non-partisan, one-house legislature.

Going into Tuesday's elections, Democrats controlled 31 state Senates and 35 state Houses; Republicans controlled 16 Senates and 14 Houses. In some other bodies, power was evenly split.

The struggle for control of legislatures centered on New Mexico, Indiana, Washington state, Oregon, Vermont, and Montana.

Democrats took a 26-16 edge to regain control of the New Mexico Senate, where a balance of 21 Republicans and 21 Democrats since 1984 had led to a shifting series of coalitions.

In Indiana, home state of Vice President-elect Dan Quayle, Democrats picked up two seats in the House to draw even with Republicans, 50-50. Democrats also picked up at least three seats in the Republican-controlled Senate.

Republicans appeared to take control of the Vermont House. With some recounts possible, the balance stood at 76 Republicans and 74 Democrats, versus 77 Democrats and 73 Republicans previously.

Montana Republicans picked up two seats to gain a 27-23 edge in the state Senate, which had been evenly divided with the Democrats at 25-25. But Democrats grabbed control of the state House, 51-49, the same margin by which the Republicans had controlled the lower house.

In Oregon, control of the House would remain undecided until about Monday, when absentee ballots are counted. Voters elected 23 Democrats and 21 Republicans, but 16 seats were undecided. Democrats previously had a 31-29 edge.

In Washington state, a tight Senate race had Republicans and Democrats with 24 seats apiece and one district still undecided. Republicans previously had a one-seat advantage, 25-24.

Pennsylvania Democrats picked up breathing room in the state House, where they widened their lead to 104-99, from 99-97 and seven vacancies.

In Ohio, Republicans slightly widened their lead in the Senate but continued to trail in the House.

Among other big states, Democrats in Texas, California and Florida maintained control of both houses, and Democrats in Illinois maintained their narrow 31-28 edge in the Senate while keeping a big lead in the House.

In New York, Democrats remained firmly in control of the Assembly and picked up at least one seat in the Republican-dominated Senate.