Northern Virginia officials trooped to the state capital today in a last ditch effort to kill two major condominium bills only to find themselves squaring off against their own local delegates.

In one committee room, Fairfax supervisors knocked heads with Del. Jack Rust (R-Fairfax) over a controversial measure they fear will leave them powerless to protect tenants against a wave of condominium conversions in Northern Virginia.

Despite their vehement protests, Rust's bill, amended by the developers' lobby to appease local officials, was sent to the Senate floor on a 6-to-4 vote.

In another committee room a few hours earlier, Arlington officials came out to denounce a bill introduced by Del. Warren Stambaugh (D-Arlington) that would block local governments from taxing rental apartments at condominium-inflated values. That bill, said Arlington officials, could mean the loss of $3 million in revenues to the county, forcing a 3 or 4 cent increase in the tax rate.

The Stambaugh bill, similar to a Senate version that was withdrawn this week at the urging of the Alexandria City Council, will come up for a vote in the Senate Finance Committee next week.

The two bills have emerged this year as the hottest issues in the annual condo wars that beset the General Assembly. In the past, Northern Virginia officials and local legislators have fought side by side in a series of unsuccessful battles for tenant-oriented condo legislation. This year, the two groups are sharply split.

"This is a special interest bill if ever there was a special interest bill," said Fairfax County Supervisor Tom Davis, one of a number of Fairfax officials who had launched a lobbying blitz against the Rust bill.

Rust, working with condominium lobbyist William Thomas, argued that Fairfax, Arlington and Alexandria have abused their powers by holding up zoning permits for condo converters in order to extract concessions for tenants.

In an effort to mollify the criticism after the bill passed the House, Rust and Thomas had proposed substitute amendments that would give Northern Virginia localities the power to enact their own ordinances requiring relocation payments of up to $500 to tenants and three-year leases at discount prices for elderly and handicapped residents who want to remain.

The Fairfax contingent was hardly satisfied. "They're ornaments," said Fairfax Supervisor Audrey Moore of the Rust amendments. "And they know full well that those ornaments are going to be stripped . . . This bill will go to conference committee at the last minute on the last night and then they're going to take them out."

The Stambaugh bill would stop local assessors from using recent sales to condominium developers as the basis for appraising apartment buildings with 12 or more units. As a result of that assessment method, tax bills to apartment owners in Arlington and more recently Alexandria have jumped by 40 percent or more in the last two years.