Negotiators for the Maryland Senate and House remain at an impasse over the state budget with only four full days remaining before the scheduled end of the General Assembly's 90-day session, Senate President Thomas V. Mike Miller said Thursday.

"We remain still at loggerheads between the House and Senate conferees," said Miller, a Calvert County Democrat. He said Gov. Martin O'Malley is attempting to act as mediator between the two sides.

The conference committees on the three unresolved bills that make up the budget package have met only sporadically since the negotiations began Monday, when talks stalled on the key measure raising income taxes. Until that matter is resolved, budget negotiators won't know how much money is available to spend. But as of Thursday afternoon, no meetings were scheduled and there were no signs of progress.

Conferees met Thursday morning to work on minor budget issues and to open discussions on another critical issue that needs to be resolved before the budget can be finalized - how quickly to shift part of the cost of teacher pensions from the state to the counties. The Senate favors a four-year phase-in; the House wants to complete the shift in three years.