For the second time in less than a week, a conservative coalition of state senators halted Senate activity to filibuster a pro-labor piece of Gov. Harry Hughes's legislative package.

The conservative coalition held the floor for three hours this afternoon, as anxious labor leaders and Hughes staff members watched from the balcony. At nearly 5 p.m., the coalition members and a majority of their colleagues agreed to recess for Easter and return on Monday morning.

Last week a similar group held up Senate approval of Hughes's proposed new labor department for 10 hours. That filibuster ended only after Senate leaders agreed not to push several other measures, including the prevailing wage bill that came up for consideration today.

Today's issue was the proposed expansion of a 13-year-old state law requiring contractors on any construction project that is completely financed by state funds to pay workers the prevailing, generally union scale, wage in the surrounding area.

The building trades unions have sought to expand the law to cover any project that is funded 50 percent or more by state monies. Last fall, during his reelection campaign, Hughes agreed to introduce a bill to this effect. His bill would exempt any project under $500,000.

Opponents of the bill have charged that Hughes is catering to the unions for political reasons and that such a change in policy would dramatically increase state costs for such major construction projects as roads, schools and state buildings.

Fiscal experts in the legislature said that, while the probable effect of the bill is difficult to determine, they estimate that state construction costs could increase by 10 percent in some areas.

"This bill is probably one of the most expensive bills the taxpayers of this state will have to fund," said Sen. James Simpson (D-St. Mary's), who began the filibuster and who threatened to stall Senate business for days. "This is a terrible bill and we should defeat it."

To document his claims, Simpson distributed a list of construction costs on a state building now going up in Charles County where the current prevailing wage laws apply.

The list showed that painters on that job are being paid more than $15 an hour--the prevailing wage as determined by a state survey of the area, which includes the Washington suburbs. Simpson said that if the prevailing wage law and such a survey were not required, a painter could be hired in Charles County for $9 to $10 an hour.

Sen. Norman Stone (D-Baltimore County), the chief proponent of the legislation, said today that the current law is "unfair because non-union contractors have an unfair advantage in bidding." Stone comes from an industrial district just outside of East Baltimore, where labor unions are regarded as the strongest political force.

Senate President Melvin A. Steinberg said that he will try to get the two sides together before the filibuster resumes on Monday. But he warned that a compromise might be difficult to reach and the filibuster could drag on until mid-week.

"This is one issue that strikes at some basic philosophical differences," Steinberg said.

If the filibuster does tie up the Senate that many days, it could jeopardize legislation considered vital to Prince George's County. A new state lottery and a new business property tax, which together will bring $16 million to cash-strapped Prince George's, must be approved by the legislature by April 11, when the session ends and all bills not voted upon are dead for the year.