ASHINGTON - When the Democratic National Committee met six months ago, Bill Bradley was an upstart challenger, unwelcome at the event, leaving Al Gore free to implore the delegates to ''stand by me.''
Tomorrow, the two will get equal billing on the stage at the committee's fall meeting, the surest sign so far that the inevitability of Gore's presidential nomination has faded among Democrats.
In back-to-back appearances, Bradley and Gore will try to rally a key component of the party faithful, the DNC's 428 members, who will make up 20 percent of the delegates next year at the Democratic National Convention in Los Angeles.
With polls indicating the vice president and the former New Jersey senator are running neck and neck in New Hampshire and New York, two crucial states in the nomination process, Bradley was invited along with Gore to attend the party's last meeting before the convention.
''Until the delegate-selection process takes place, no nomination is absolutely certain, and I don't think the vice president would want to take that for granted,'' said Jim Roosevelt, a DNC member from Cambridge who said he is staying neutral.
Considering the organization's overwhelming support for Gore, the invitation for Bradley to speak represents a seismic shift for this slice of influential Democrats, especially after the earlier snub to Bradley.
At the committee's meeting in March, Bradley was shut out of a speaking role, while Gore appealed to the members to support his quest to succeed President Clinton and finish the work they started.
During that spring session, the Bradley campaign had arranged an informal meet-and-greet reception for DNC members, but the White House stepped on the event by scheduling its own South Lawn reception at the same time that featured the president. Bradley ended up canceling his reception and dispatching his wife, Ernestine, and several aides to the DNC conference.
DNC spokesman Rick Hess said Bradley was not invited in March because neither he nor Gore had formally declared their candidacies for president. ''The vice president spoke at the meeting in his official capacity as vice president,'' Hess said.
This time, however, is quite different. ''They are both good Democrats, and we are happy to have them,'' Hess said.
The deferential treatment of Bradley is a reflection, many Democrats say, of a new reality that Bradley has emerged as a serious candidate for the nomination.
''People are looking at it as a race,'' said James J. Zogby, a DNC member who is also president of the Arab American Institute. ''I'm committed to the vice president, but I'm noticing what everybody has, and that is this is becoming an election. You've got two people coming to talk.''
A Democratic strategist, who asked not to be named, said that although the DNC is an ''all-Gore operation,'' Bradely cannot be counted out. ''I don't think the group is entirely in the tank with Gore,'' the strategist said. ''They are in the states, and they are hearing everything we're hearing. Bradley is doing pretty well, and I think Bradley will do pretty well there.''
Not only has the DNC reached out to Bradley during the fall meeting that began yesterday, but the White House is exercising more restraint. Clinton will address the meeting today.
White House aides familiar with Clinton's speech do not expect that he will make an overt appeal for the DNC members to support Gore.
Anita Dunn, a Bradley spokeswoman, said that while Bradley may still be viewed as an outsider, there has been an attempt by the DNC ''to at least keep us periodicially informed as to what they are doing.''
A Gore spokesman, Chris Lehane, said that rather than viewing Bradley's new status as a knock against Gore, the campaign welcomed the opportunity for Democrats to ''compare and contrast'' the candidates.
