Senate Minority Leader Robert C. Byrd (D-W.Va.), predicting that the Democrats will regain control of the Senate in this year's elections, said yesterday that he has lined up a majority of Senate Democrats behind his bid for a sixth two-year term as the party's Senate leader.

"I have a majority, I have enough," Byrd said at a news conference with Minority Whip Alan Cranston (Calif.) and Sen. Daniel K. Inouye (Hawaii), the secretary of the Democratic Conference, to announce their plans to seek reelection to their current leadership posts.

Byrd's announcement that the same "leadership team" would seek reelection together was clearly an attempt to discourage a challenge to his leadership by Sen. J. Bennett Johnston (D-La.). Byrd's claim to have already rounded up a majority was also in keeping with tactics normally used in these behind-the-scenes struggles for party leadership in Congress.

Johnston, too, exuded confidence Wednesday in confirming his plans to challenge Byrd, but the minority leader yesterday appeared unperturbed by the prospect of a contest over the post he has held since 1977.

"I told Sen. Johnston he is going to make a fine chairman of the Energy Committee," Byrd said. Johnston, if he is not elected Democratic leader, is in line to take over the Energy Committee if the Democrats regain control of the Senate, where the Republicans currently hold a 53-to-47 majority.

Byrd said that besides his Democratic colleagues, he has talked to most Democratic candidates for Senate seats about the leadership contest. He said he was announcing his plans now "to put to rest speculation and to present the image of a leadership that is united."

Inouye, who had been rumored to be considering a challenge to Byrd, praised Byrd for his "innovative approach of sharing leadership" since the 1980 elections, when the Democrats lost their Senate majority for the first time since the mid-1950s.

Byrd pledged to continue "that kind of sharing of leadership" in the 100th Congress, which convenes next January. He also played down criticism that he, Cranston and Inouye are poorly equipped to speak for the party in a political era increasingly dominated by television, including live coverage of Senate floor proceedings.

"I have no problem with television," Byrd said. "I have no doubt that the Senate Democratic leadership and Senate Democrats will present an image of a party ready to take leadership." Said Inouye, "We may not be a bunch of Charlton Hestons but we've had more unity in the last six years than I can remember."