TRENTON – Senate President Steve Sweeney’s (D-3) late challenge today on the longest day of the year in New Jersey politics concerned his corporate business tax (CBT), which required some late poking of allies in both parties.

It’s likely a fluid situation, or was until this morning.

And tight.

A source close to the Senate President said 21 Democrats have committed their support to the CBT, the revenue-generating alternative to the millionaire’s tax option favored by Governor Phil Murphy, and a key part of Sweeney’s budget. With little cushion in his caucus, three sources told InsiderNJ that Sweeney in the last number of hours gauged potential support of at least a couple of Republicans on the issue.

“He’s fine on the budget,” one of the sources said, “but he was looking for CBT support outside the caucus, with Republicans.”

The Sweeney ally insisted that the Senate President is confident that he has the necessary votes for both the budget and CBT, and that the 21 committed votes in the case of the latter would hold. The three other sources from three separate Statehouse strata insisted he would need the GOP, however, for CBT; that at least a couple of Democrats were wobbling.

While Sweeney worked the phones ahead of a scheduled noon budget vote in both houses, Murphy was also reaching out to legislators, “desperately,” according to a veteran staffer.