Rabbi Jonah Pesner, a Democrat who had earlier floated the idea of a Senate bid, said today he will not run in the special election for the Massachusetts seat soon to be vacated by Democratic Sen. John Kerry.

Democratic Bay State Rep. Edward J. Markey remains the only declared candidate for the Senate special election. Rep. Michael E. Capuano, D-Mass., announced he had decided against a run earlier this week. Markey is supported by the Democratic Senatorial Campaign Committee and has worked to clear the Democratic field — so far with great success.

In an email to friends and supporters, Pesner wrote that the last few weeks had  “been among the most exhilarating of my life.” But, after consideration, “[a]t this time, I have decided not to run for the United States Senate,” he wrote.

Pesner left open the possibility of a bid down the road. “Perhaps there will be a time in the future when the call to elected leadership will make sense for me and my family,” he added.

Kerry is expected to soon be confirmed as secretary of State, leaving the Senate seat open. Democratic Gov. Deval Patrick will then appoint an interim senator and set the date for the special election. Former Sen. Scott Brown, R-Mass., who was ousted in November by Democrat Elizabeth Warren, has not yet said whether he will run in the special election.