Virginia Gov. John N. Dalton vetoed the General Assembly's House redistricting plan yesterday, saying the plan had too many oddly shaped districts to be constitutional.

That action by the Republican governor means the Democratic-dominated House likely will be called back into session next month for the third time this year either to redraft the plan or override Dalton's veto. Northern Virginia's districts were not at issue in the veto.

The assembly would need a two-thirds vote in both the House and the Senate to override the veto. Some legislators said yesterday it seemed unlikely that there were 67 votes in the 100-member House and 27 votes in the 40-member Senate to override Dalton's veto, especially after the surprisingly close votes to approve the House bill at last week's special redistricting session.

"I cannot imagine even in my wildest dreams that they would come up with the votes necessary to override that veto," said Sen. Wiley Mitchell (R-Alexandria). The Senate approved the House bill by a 19-to-15 vote last week and one of those affirmative votes was mistakenly cast by Mitchell, who said he pushed his lever the wrong way.

"I think most of the people who voted against it were people who thought the bill was a bad bill and would applaud the governor's veto," Mitchell said.

But Del. Warren Barry (R-Fairfax) said yesterday he feared the House plan would be decided by a strictly partisan vote. There are 74 Democrats in the House and 31 Democrats in the Senate, more than enough to override the veto.

"I'm not sure the Democrats who voted against this bill will hang in there when it comes to a partisan override of a Republican governor," said Barry, a six-term incumbent. "I saw a brand new game of hardball, partisan politics taking place which is totally new in the 12 years I've been down there."

Dalton said the House plan, which has only 10 districts containing a single delegate, failed to meet the state constitution's requirement that districts be compact.

"It is my belief this can best achieved through single-member districts," Dalton said. Many black leaders and civil rights groups have been lobbying for a single-member House plan since the first rough redistricting plans were sketched out almost a year ago. Earlier this year those groups successfully sued to have the House plan declared unconstitutional by a federal court in Richmond. An earlier House plan had been rejected by the Justice Department on the grounds that it diluted black voting strength in the state.

"We congratulate the governor and the General Assembly because they're getting another chance to do the thing right," said Judy Goldberg, a lobbyist with Virginia's American Civil Liberties Union. "They've had more chances to do this right than anyone anticipated they would need or get."

Dalton did sign the Senate's third attempt at a redistricting plan, which gives blacks a slight majority in one of Norfolk's two districts. That plan must now be approved by the Justice Department, which rejected two earlier plans this year. The redistricting deliberations in the House and Senate have already cost Virginia an estimated $1 million.

One of the happiest House members to hear of Dalton's veto yesterday was Robert Bloxom, a Republican who currently represents the counties of Accomack and Northampton on Virginia's eastern shore in a single-member district. Under the House plan just vetoed, Bloxom's district would have been enlarged into a two-member district to include three more counties and the city of Poquoson, now separated from Bloxom's district by 20 miles of Chesapeake Bay.