BOSTON (AP) — Democratic U.S. Senate candidates Edward Markey and Stephen Lynch are scheduled to appear together on the same stage for the first time in the special election campaign.

The Service Employees International Union says the two congressmen have confirmed they will attend a candidates' forum in Boston on Saturday sponsored by the labor organization.

SEIU says it has also invited the three Republican candidates, former US Attorney Michael Sullivan, state Rep. Daniel Winslow and businessman Gabriel Gomez. It was not immediately clear if any of the GOP hopefuls planned to attend.

The union's membership includes hospital employees, janitors, social workers and other professions.

The special election to fill the Senate seat formerly held by John Kerry is set for June 25. The Democratic and Republican primaries are April 30.