President Obama will speak to House Democrats before they vote on the health care bill, even if the vote is pushed to Sunday or Monday.

White House Press Secretary Robert Gibbs told reporters in his daily briefing that due to the shootings at Ft. Hood yesterday, schedules changed and that's why Obama is planning to go to the caucus tomorrow instead of today as originally scheduled.

"The president wanted to go closer to the vote," he said.

Obama "will go to Capitol Hill to advocate for continuing that progress," Gibbs said.

As TPMDC reported earlier, Obama is getting more active on the issue and Vice President Biden is on the phone with lawmakers today to speak about health care.

Gibbs said the message on the calls and in the caucus meeting will be to "pass health care."

"The sales pitch is simply that we're on the cusp" of passing health care reform that the country has needed "for decades."

The message will be "Do this for the country, do this for your constituents, do this for the people you represent," Gibbs said.

Gibbs added he assumes Obama will answer questions and "rally the troops."

Meanwhile, Organizing for America, the campaign arm of the Democratic National Committee, is injecting a sense of urgency into the issue by letting supporters know about the upcoming vote.

"All signs point to it being incredibly close, possibly even coming down to a single vote," Mitch Stewart, OFA's director, told 13 million supporters in an email.

In an ironic twist, the email message to D.C. residents asked them to call Del. Eleanor Holmes Norton, who does not vote on final passage of House bills because of the city's status.

Gibbs said negotiations are still ongoing on sticking points in the health care bill, including any funding for insurers that provide abortions and coverage for illegal immigrants.

"Tomorrow will not be final vote on the bill coming to his desk," Gibbs said.