"There is a time in every presidency where you gotta start doing things that are unpopular with some groups, outside forces come in play and the joy ride is over," a Republican strategist observed yesterday. "Bush's time had to come. It's a wonder it lasted so long."

A variety of Bush advisers and outsiders suggested in interviews yesterday that a new phase of the Bush presidency has begun. The painful decision to acknowledge the need for new taxes was the most striking example of this, but so too were the president's less visible struggles over civil rights, parental leave and environmental issues. Suddenly this summer, Bush found that he could not avoid a series of tough decisions that were never forecast in his presidential campaign.

Over the past month as a number of issues closed in on him, Bush has been a study in the difficulty of reconciling campaign promises with governing. His familiar desire to make decisions by splitting the difference -- what friends call the "have-half Bush" -- has been challenged by the need to make difficult choices over which the president has struggled aloud:

To a group of Western politicians on choosing between protection for the northern spotted owl and what some see as the potential loss of nearly 30,000 jobs in the timber industry, he said, "I reject those who would ignore . . . the economic consequences of the spotted owl decision" but "I also reject those who do not recognize their obligation to protect our delicate ecosystem. Common sense tells us to find a needed balance."

To a group of civil rights leaders pressing for his support for the Civil Rights Act of 1990, he said, "I want to sign a civil rights bill" but "I won't sign a quota bill."

To questions on how he could abandon his campaign pledge to ensure women do not lose jobs because of pregnancy or family crisis, Bush said that pledge "did not go to what they call mandated benefits." When he made the pledge, White House press secretary Marlin Fitzwater said, it may not have been stated but was "implied" that Bush wanted firms to protect these jobs on a voluntary basis.

To questions on why he was breaking what many view as his most fundamental campaign pledge by agreeing to the need for tax increases, Bush thus far has offered no explanation. But Fitzwater, in an explanation aides say fit all campaign divergences equally, said Tuesday, "We feel he said the right thing then and he's saying the right thing now. Everything we said was true then and it's true now."

Early in Bush's presidency, Robert M. Teeter, Bush's campaign pollster and a key political adviser, described his hopes for the first months of the Bush presidency in terms of a savings account.

With no major crisis to solve, Teeter said, Bush would not have to "spend" his political capital early by making tough choices. Instead, he could reach out to minorities, women, the environmental community and others who had been alienated from the GOP to make new deposits to his popularity account that he could draw on when the tough times came.

Another Republican, comparing Ronald Reagan's first year in office to Bush's, said the president is struggling to find a balance between competing forces such as business interests and the environment "not because there is anything peculiar about this time period in a presidency but because there is something peculiar about Bush."

The strategist noted that until Bush, a string of recent presidents came to office pledging to fix what the former inhabitant of the White House had broken.

Bush could run what the strategist called a "keep on keeping on" campaign and was not pledged to fixing any major broken piece of the Reagan presidency, in which he was a key figure.

As a political candidate, Reagan "had an agenda, an ideology and a crusade," the strategist said. "Because he was the ideologue that Bush is not," the official said, "Reagan didn't have to make all these tough calls because they never got to him. No one would suggest to Reagan that the protection of the spotted owl in any way was worth 30,000 jobs. He just never campaigned as the Environmental President so it was no problem."

Bush, one source said, "ran a campaign for class president. I like everyone and everyone should like me. And everything will be great." Now, said the official, "it's not the senior class he's running, it's the country. Sometimes it's just not that easy. This is one of them."

Bush's advisers, and even some Democratic strategists, predict that while some of his decisions will peel off some of his support, broken campaign pledges will not doom him if the economy holds up and he is seen as having taken the lead in maintaining economic health.

It is axiomatic among most political experts that a good economy ensures Republican retention of the White House outside of war or major scandal.

"If the economy is in trouble," said one Bush adviser, "it is the only issue and you are in trouble. Nobody will care if you're the Education President or the Spotted Owl President. Nobody will care if you promised to solve global warming and it's not solved yet."

Conversely, said the adviser, if the economy is in good shape "you have a cushion. You can take some risks. You can make some decisions some people won't like." That, the adviser said, is why Bush, weighing the taxes pledge over the fears for the economy, had to do what he did.

"Good government really is good politics," said Mary Matalin, chief of staff of the Republican National Committee.