All that was missing from a reception of Native Americans last night was a banner proclaiming "New Partnership." A crowded Capitol Hill room fairly crackled with elation at the success of 12 Indian groups in joining for a common purpose and for the end of what most saw as indifferent treatment from the White House.

"This is probably the first time all the Indian organizations have ever gotten together," said Val Cordova of the Native American Rights Fund. "We are usually vying for the pieces."

Busy embracing old friends, LaDonna Haris, one of the best-known spokespersons for Native American rights, said, "In the past we have all been going our separate ways."

The "New Partnership" also extends to the Reagan administration, explained a beaming Peter MacDonald, head of the Navajo nation. "The Reagan people have already called us for advice and input" on energy issues, he said."Once the Carter people had an energy conference and left us out. Later their excuse was there wasn't any room. So, for us, the New Beginning is translated into a New Partnership."

All this fellowship and good will took place at a wine, vegetables and cheese reception to honor some concerned legislators. And, although Sens. James McClure of Idaho, John Melcher of Montana, Slade Gorton of Washington, and Reps. Morris Udall (D-Ariz.), Raymond Kogovsek (D-Colo.) and others were present and circulating, that purpose was almost lost in the discussions of the new beginnings.

"Communications did not exist with Carter," said Ron Andrade, the executive director of the National Congress of American Indians. "He would veto an Indian bill and not call us. He would pass regulations and not call us. They pulled away from the tribal government as the key leadership and by the time they decided to talk to us, it was too late." According to the groups, the voting pattern of the country's 1.5 million Indians matched the general population's swing to the Republicans, a fact endorsed by several Republican National Committee staffers at the party.

Even though many of the Native Americans opposed the choice of James Watt as interior secretary, aren't certain of the future of the interior's Bureau of Indian Affairs and are nervous about social-service budget cuts, they are willing to give the Reagan team a chance. "We have got to bring home to this administration that their issue of states' rights is our issue. The tribes should be treated as a state," said Ed Gabriel of the Council of Energy Resource Tribes.