To Jim Wright, being majority leader is one long juggling routine

On a day that begins with an early-morning meeting and ends with a barbecue fund-raiser where he'll be expected to play the harmonica, majority leader Jim Wright has only 30 minutes for lunch in the House of Representatives dining room. Even that is interrupted by warning bells, which send him upstairs to the House floor for a vote.

''I feel like a person constantly juggling five balls in the air,'' he says, returning to an unfinished salad. Then someone tosses in a new ball, he says, and he must decide which one to throw away.

The Texas Democrat, a legendary orator given to using metaphors, whether in the House chamber or in conversation, has not overstated his case. No. 2 in the Democratic leadership, he arranges the House schedule and looks after individual House members' needs. He pieces together coalitions to push through his party's domestic programs. And he helped persuade a reluctant Democratic House to give President Reagan authority to keep United States troops in Lebanon.

But while juggling those concerns, majority leader Wright has others that he never drops. One is taking care of his Fort Worth district, a blend of moderates and conservatives whose prosperity partly depends on the federal grants and contracts he has secured. The other is his hope to be speaker of the House after Thomas P. O'Neill Jr. (D) of Massachusetts steps down.

The speaker post is ''the greatest legislative job on earth,'' says the man who is heir apparent. ''I think it is natural for anyone to want to attain the pinnacle of his profession.''

Although he maintains that he doesn't ''hunger and thirst'' for the job, the Texan points out that he has history firmly behind him: The House has not turned down a majority leader for speaker in recent years.

''I'm in a relatively strong position,'' he says. And it's hard to find anyone on Capitol Hill who disagrees.

But Jim Wright is not a man to rest on history. Prone to watch details, he leaves few unattended when it comes to being party leader. Most of his days are spent talking and listening to members on the House floor or just off the chamber in his Capitol office.

The majority leader is a ''combination of evangelist, parish priest, and part-time prophet,'' Mr. Wright is fond of saying. ''You have to be a peacemaker within the family,'' he says, adding with Wrightian flourish: ''You have to find that elusive grail of harmony among this most heterogeneous mix of opinionated individualists.''

Friends and critics alike credit him with diligence. He is an energetic fund-raiser for his colleagues' campaign funds. When the freshman Democrats arrived after the 1982 elections, Wright was there to offer advice. Contributions from his Wright ''Appreciation Fund'' had helped some win their seats.

''We knew right away who Jim Wright was,'' says Rep. Jim Bates, a California freshman.

Wright is no less careful about retaining ties with the folks who have elected him every two years since 1954. If a speaker needs a secure district so that he can focus on national affairs, Wright's fits the bill.

Except for a core of conservative businessmen who are determined foes, Wright has captured a healthy majority even among conservatives in his district.

''I don't think Jim has an enemy in this town,'' says an aerospace executive who lives near Fort Worth in suburban Hurst, Texas, and is a Reagan Republican. ''I don't agree with Jim Wright, but he does so much for the region.''

Wright's influence is visible from the spiffed-up, remodeled downtown Fort Worth - courtesy, in part, of a $9 million federal grant - to the stockyard area , where tourists can see the Old West, restored with aid from federal money. The congressman is also in a position to help his district win lucrative contracts for its defense industries.

Moreover, the tradition of having a powerful Texan in Washington goes deep in a state that has produced two House speakers and a president this century.

''Even if I don't like the way Jim votes on some particular issue, the prospect of having Jim as speaker of the House means more to me,'' says Gerald Summerford, an assistant district attorney and a Forth Worth precinct chairman who, when 16, joined Wright's first congressional campaign.

At the time of that race, Wright had built up a company that promoted businesses in small towns and counties in 40 states and had become the ''boy mayor'' of Weatherford, Texas. But ever since he was a sophomore in college, he says, he wanted to be in Congress.

Once upon a time his aspirations went as high as the White House, and he failed twice in bids for the Senate during the 1960s. Now his sight is set only on the speaker's chair. One key is his relationship with Speaker O'Neill, whose liberal views have not always jibed with Wright's moderate voting record. But the two stood close together and faced the ire of many Democrats last month on the matter of giving the President 18 more months to keep US marines in Lebanon.

''Jim Wright's stock is very high with the speaker'' and seems to be rising, says O'Neill aide Christopher J. Matthew. ''They were strong partners on Lebanon.''

Wright has also shored up doubts among some of the younger, more liberal Democrats by turning against the MX missile, which he once favored. The majority leader holds that the switch had ''little to do'' with pleasing new members and more to do with the $25 billion MX price tag and growing federal deficits. But his position has still been strengthened.

If the intense, conscientious Wright has a liability in his quest for the speakership, it is his temper. He blames it on ''fighting the clock.'' And it appears with some regularity. Flashes of Wright anger with his Democratic colleagues over Lebanon led one Northern-state member to conclude, ''He's talented, hardworking, serious, but temperamentally he's diminishing his chances of becoming speaker.''

That is a minority view, not even shared by Rep. David R. Obey (D) of Wisconsin, who led the Democratic rebellion against the Lebanon agreement. He and Wright had a ''stern and blunt exchange'' in party caucus, says Representative Obey, over whether members of top committees had a ''responsibility to follow the leadership.''

But Mr. Obey plays down the disagreement.

''I think he does a good job,'' he says of Wright, adding that once Mr. O'Neill retires, ''I'd a whole lot rather be in Jim's shoes'' than anyone else's. ''I don't know of anybody who might challenge him.''

Wright's support comes from a range of viewpoints in the party. ''I think that Jim has worked hard and earned a shot at it,'' says Rep. Charles W. Stenholm, a fellow Texan who heads the ''boll weevil'' caucus of conservative Democrats.

''I don't think his ideology or feelings are so far off that it injures his leadership capability,'' says Rep. Richard A. Gephardt of Missouri, one of the younger corps of leaders among moderate-to-liberal Democrats.

Like many of his colleagues, Representative Gephardt sees Wright's speaking skills as a major strength. He points to Wright's carefully honed and polished speeches, which he delivers in a low-key, deliberate style that builds to a crescendo of oratory that pricks up ears in a normally inattentive House.

Rep. Tom Loeffler (R) of Texas calls Wright ''the most articulate member of the US Congress.''

''I don't think it's a question of oratory skills,'' protests Wright. ''You have to make sense.''

And does he sometimes persuade wavering members with his speeches? ''Sometimes,'' he says.

He is also persuading many that he's the logical one to step into the speaker's job someday.