Question: What did the country music banquet at the White House Monday night have in common with the Panama Canal?

Answer: Sen. James R. Sasser (D-Tenn.)

That connection may appear obscure, but it tells a lot about the process through which the Carter administration and the Senate have gone in recent weeks while the president was seeking treaty votes. It also tells a little about the political sophistication - or lack of it - in the Carter White House.

For two weeks, the administration had been on notice that it could no longer loyal Sasser for granted on canal treaty No. 2. He had made plain that he expected a little more consideration on items, big or small, affecting him and the state of Tennessee. Other senators have been making similar complaints.

Sasser had even cast a vote or two in favor of restrictive amendments to canal treaty No.2 that had apparently made administration loobyist sit up and start worrying.

Then, Monday afternoon, the day before the big vote on treaty No. 2, Sasser had his office call the White House to find out who else besides Loretta Lynn, Conway Twitty and Sasser was going to attend the country music reception that evening.

Once again, the senator from Tennessee got a cold shoulder. "They refused to give me a list of who was coming," Sasser exclaimed. He seemed genuinely baffled, and for good reason.

Until early this month, the White House had been automativally counting on Sasser, among others, as a sure vote fortreaty No. 2, but Sasser had been growing increasingly exaspertivity to "the wishes and needs of the people who have been their strongest supporters."

"They keep expecting us to fall on our swords," Sasser said unhappily in an interview the day before the vote, "But there's been very little reciprocity."

What finally ticked Sasser off two weeks ago - after suffering through administration opposition to such controversial projects as the Clinch River fast-breeder reactor - was, he concedes, no great shakes. But it was, according to one close associate, sort of a last straw.

Two weeks ago, Sasser heard that the Department of Housing and Urban Development was about to reject federal funding for a world's fair in Knoxville, Tenn.

Dubbed "Energy Expo '82," this was the same proposed fair that former budget director Bert Lance's banker friend and creditor, Jake Butcher, has been promoting. Lance got Butcher, who is serving as chairman of the Expo and his brother, C. H. Butcher, in see Treasury Secretary W. Michael Blumental about the project last year. It would reportedly displace 64 business with some 1,300 employes in a section of downtown Knoxville, but the city nonetheless applied this year for $13.8 million in federal funds under a new HUD program that is supposed to create jobs.

HUD Secretary Patricia Roberts Harris announced the first $150 million worth of grants under the program April 5. "Energy Expo '82" was ignored.

Sasser first heard, from someone in Knoxville, that the project had been rejected outright. He claimed down a bit when he learned that the application is still eligible for reconsideration with the next wave of grants under the $400-million-a-year program. But he was still miffed.

For the record, Sasser, a freshman who got elected with a Cartersque campaign, denied that he was trying to "send them a message" with his interim votes on restrictive amendments. But associates say "he's pleased that people read it that way." Said one: "He would have preferred the status quo in Panama anyway."

The president was well aware of Sasser's chagrin. He even mentioned it during his weekend meetings at Camp David with Cabinet and White House staff members as a casebook example of how not to run the government.

According to one administration official, Carter ticked off "a series of things involving Sasser that by themselves aren't terribly consequential, but in accumulation, are potentially disastrous."

Then came the little contretemps over the country music guest list.

Sasser says he blames "Cabinet government" for most of his frustrations, and not the president, who remains quite accessible. In fact, Carter nailed down the Tennessean's treaty vote toward the end of the countrymusic banquet with a private conversation in the Oval Office. "He said he just couldn't tell the president 'no' face to face," a Sasser aide said.

The senator from Tennessee, however, is still unhappy. "On matters that are not of such critical importance to the country," he says, "the administration's wishes, one way or the other, are becoming a matter of no consequence to me."