Like his friend and fellow conservative Ronald Reagan, Texas Gov. Bill Clements swept into office promising to cut the government down to size. He said he would slash taxes by $1 billion, reduce the state work force by 25,000 and bring sound management to state government.

But even in conservative Texas, Clements has failed to achieve immediate results. Two years after his inauguration as the first Republican governor in 100 years, Clements is still asking for tax relief, his promise to cut out 25,000 state employees over four years is still at least 24,000 short and other initiatives have either been blocked or delayed.

But Clements, a former oil drilling executive and Pentagon deputy secretary, has made a big impact. He's done it largely by making good on his promise to be an activist governor, and his political ally Reagan might take a lesson on how a chief executive can influence a bureaucracy by the sheer force of his personality. In ways the Democratic establishment here doesn't fully appreciate, Clements has already left his mark on Texas' state government.

While the parallels between government in Washington and government in Texas are sometimes imprecise, the story of what has happened since Clements took over this Democratic state is insructive to the incoming Republican administration and to the Democrats who are already feeling out of power.

Since his election in November, Reagan has given the impression that he will be a detached chief executive, a chairman of the board. Clements has acted more like the chief operating officer, gathering together the heads of various departments for regular talks on management techniques, looking in on other state officials who had never been visited by Democratic chief executives, and making himself regularly available to the press. All this has made Clements larger than the limited power of his office, in sharp contrast to his two Democratic precedessors, and his influence is clearly felt.

He has delivered on his promise to improve the management of the state government, helped slow the growth of state spending and stopped the growth of the state bureaucracy. And, through his appointments, he is systematically affecting policy and management in state agencies.

"I am a manager," Clements said the other day in his office in the Texas capitol. "I didn't exactly come into this job barefoot in that regard."

But Clements' priorities and his high-handed style are not unanimously admired. He is bitterly opposed by the state's small collection of liberals and the Texas labor movement, which find themselves even further from power than they are accustomed to being.

"He reflects the attitude of people in Texas who want to take the state backward rather than forward," said Harry Hubbard, head of the Texas AFL-CIO. "He indicates that every time he holds a public meeting or is quoted in the newspapers. He's made it clear his main objective is to strengthen the corporations even more than they are now.

"I think that in the next few years, especially with him advising Reagan, that that will continue, and the people of this country are going to see that the corporations can't run it either," he said.

When Clements took over in January 1979 as the surprise winner of an extremely close election, the legislature had its own agenda ready.

"I had to go along and play catchup ball with a fast-moving train. I barely caught the caboose," he said.

But he didn't hesitate to tell the independent legislature what he thought the people of Texas had asked for by electing him.

At the time, state spending, propelled by an enormous surge in population, was increasing 25 to 30 percent every two years. The number of state employees was growing as rapidly as in any major state.

Clements' first step was to ask for more power. The founding fathers of the Lone Star State had made their chief executive one of the weakest in the nation, so powerless that Lyndon B. Johnson often wondered why his protege, John B. Connally, would even want the office. Power is so decentralized that the governor doesn't even appoint his cabinet.

"The legislature is so powerful, it can run the state," said George Christian, former press secretary to Johnson and now a political consultant in Austin. "A governor doesn't have to get in the front line if he doesn't want to. But Bill Clements would charge hell with a bucket of water."

Bucket in hand, Clements asked for more authority over the state budget and over appointments to the more than 200 boards that run the various state agencies. He also called for a return of $1 billion in projected surpluses to taxpayers and for a series of constitutional amendments that would make it more difficult for the legislature to raise taxes.

He asked for an amendment to give Texans he right of initiative and referendum. He called for a wiretapping bill to help cut down on drug smuggling in Texas. He called for a back-to-basics movement in education, including competency testing for teachers, and made higher teacher salaries -- a major issue of his opponent during the 1978 campaign -- a peripheral part of his overall education program.

As the 67th legislature convened, here last week, Clements is asking once again for nearly all of these items.

It is that record that leads powerful Democrats such as Lt. Gov. William Hobby to conclude that the effect of a Republican administration here is minimal. But that is only part of the story.

Through his appointments, Clements is altering the balance of power in the government. Most state agencies are run by boards whose members' terms are spread over a six-year period, making it difficult for any governor to make sweeping changes immediately.

But Clements, more than past governors, has used his one clear power effectively. He not only looks for managers in his appointments, but insists that his appointees believe in his philosophy of government.

"The message gets to each appointee before he is appointed," said Tobin Armstrong, Clements' appointments chief. "Each has a clear understanding of what Clements' philosophy is for managing state government, what the governor's objectives are in that particular area, and his determination to make it a working appointment, not an honorary job. He feels that unless he can bring people in who agree to a game plan, the plan won't get carried out. It's just that simple."

Critics say Clements' appointees are like Reagan's Cabinet. "They're all alike," said one state official. "There aren't many blacks, women or other minorities."

Armstrong disagreed. "We've done a whale of a good job with minorities and the sexes," he said, but when asked for a breakdown, he said he had no numbers to prove his point.

Clements may not have delivered on his promise to eliminate 25,000 state employees, but through a highly publicized campaign he has intimidated the agencies into thinking twice before adding more jobs.

"This is no laughing matter," Clements said when it was suggested to him that he was still far short of his campaign pledge. "I'm absolutely serious about it. Stopping the momentum of the fastest-growing state bureaucracy in the United States is no mean feat."

And while state spending continues to rise sharply, the budget proposed by the Legislative Budget Board is tighter than in recent years, even while calling for a 21 percent increase over the next two years.

Clements' flinty approach and his devotion to private industry have sometimes backfired. He paid $24,000 for a private appraisal that was no better than the job done by the General Land Office.

And when he eliminated the extremist-sounding (by Texas standards) Environmental Management Division of the Lands Office, cutting 27 employees and saving the state about $600,000, Land Commissioner Bob Armstrong found himself without a division that he said had effectively kept environmentalists and industry heppy with the way the Texas coastline was opened up for exploration.

Clements hesitates to suggest how his experience could be useful to the new president. "There are vast differences between what happened here and what will confront Mr. Reagan in Washington," he said. "I wouldn't presume to suggest to him at all. He knows I'm available for consultation. All he's got to do is pick up the phone and call."