Gov. Jeb Bush (R) has been promising to pull off what would be a remarkable feat of addition by subtraction: End affirmative action but simultaneously increase minority enrollment at public colleges in Florida.

Bush says Florida can boldly do what no state has done before by adopting his "Talented 20" rule, which would loosely guarantee admission to high school seniors in the state who graduate in the top 20 percent of their class. Texas has a similar 10 percent rule which, after three years, has just about restored undergraduate minority enrollments to the levels they had reached before a federal court banned affirmative action in the state. And California has adopted a 4 percent rule that will take effect in 2001.

But if Florida is to succeed in enrolling more minority students, it will take more than Bush's Talented 20 program. In fact, according to statistics provided by Bush's office and the Florida Board of Regents, at least 40 percent fewer minority students would become eligible for admission under the new rule than the number enrolled this year through affirmative action.

But that doesn't mean Florida colleges won't be able to increase their minority enrollments; only that they may have to resort to a variety of other measures to do so. According to aides to the governor and the board of regents, colleges are being granted license to do almost anything--short of directly considering race or ethnicity in admissions--to attract minority students. Using geographic distribution, income and other factors that could act as proxies for race are all being considered.

"If any university feels that it does not have sufficient skill, experience or ideas to maintain a diverse student body in a race-neutral fashion," said Chancellor Adam Herbert, an African American who headed Bush's transition team and has staked his reputation on the success of the governor's plan, "I will personally provide technical assistance to them." Currently, minority students make up about one-third of the total enrollment in Florida's public colleges.

In Texas, California and Washington, states where affirmative action has been banished by court decision or referendum, minority enrollments dropped immediately, particularly at selective colleges such as the University of Texas in Austin and the University of California at Berkeley.

In Florida, Bush has proposed his plan to end affirmative action in a bid to head off a more far-reaching referendum drafted for next year's ballot and to prevent a political backlash that could damage the presidential prospects of his brother, Texas Gov. George W. Bush (R). Various aspects of Florida's new admissions plan will require final approval next year by the board of regents, the state Board of Education or the legislature.

Some critics have characterized such guaranteed admissions rules as an unconstitutional disguise for continued affirmative action. "It is pretty clear these are a means once again to use race as a factor," said David Gersten, vice president of the Center for Equal Opportunity.

The arithmetic of ending affirmative action in the nation's fourth-most populous state goes something like this: First, subtract 2,000 minority students whose race or ethnicity helped get them into college. Then add 400 to 1,200 from the top fifth of their high school classes who otherwise would not be academically eligible for admission, resulting in a net loss of 800 to 1,600 minority students.

Exactly how many minority students, primarily Hispanics or African Americans, might benefit from the Talented 20 rule remains somewhat uncertain because the "guarantee" of admission comes with a big caveat: Beneficiaries must also have completed 19 required courses in high school.

Bush's office found that 400 minority seniors in the top fifth of their classes last year had taken the 19 courses, while 800 lacked either foreign language or science courses. His plan raises the possibility of allowing the latter students to enroll and make up their missing course work during the first two years of college.

But even if these students are included, Bush's goal of increasing minority enrollment will require colleges to admit more than 800 additional minority students who otherwise would not qualify, presumably by substituting other social factors for race or ethnicity.

"Universities will still have the option to use other criteria, and they will unintentionally correlate with race," explained Brian Yablonski, a policy analyst in Bush's office.

Several factors under consideration would capture disproportionate numbers of minorities, such as socioeconomic status (being poor), geography (coming from an inner city or rural area), parental education (being a first-generation college student) and educational disadvantage (attending low-performing schools, where minorities constitute 74 percent of students).

Florida colleges can also target their recruitment efforts to minorities and offer $4 million in minority scholarships, activities not permitted under broader legal bans affecting Texas and California.

Bush's plan has the backing of state college presidents, including Frederick Humphries of historically black Florida A&M University. Charles Young, acting president of the University of Florida, initially expressed reservations about the impact on minority enrollment at the state's flagship school, but has changed his opinion.

Civil rights groups have also mostly laid back for strategic reasons, seeing Bush's plan as preferable to the likely passage of a statewide referendum banning affirmative action. The plan's most vocal critic thus far has been Rep. Corrine Brown (D-Fla.), an affirmative action supporter and member of the Congressional Black Caucus.

For undergraduates, the ban would take effect for students entering college next fall. But concerns expressed by Brown and others about minority enrollment in law school and other graduate programs prompted Herbert to delay ending affirmative action at that level for one more year.

The Math of Putting `Talented 20' in College

Florida Gov. Jeb Bush's "Talented 20" plan combined with current course requirements would leave as many as 1,600 fewer minority students eligible for state public colleges. However, the plan might allow those students to make up the required course work after they have enrolled.

Two sets of requirements

1,200 minority students would be newly eligible under Bush's standard for admission because they graduated in the top 20 percent of their high school class . . .

Newly eligible minority students: 1,200

. . . but 800 would lack some required courses . . .

Lack courses: 800

. . . leaving 400 who meet both requirements.

400 eligible (Without provisions for making up courses.)

Affirmative action vs. top 20 percent

2,000 minority students were admitted to Florida state universities for the 1999-2000 school year under current affirmative action rules . . .

Affirmative action: 2,000 minority students

. . . and if "Talented 20" replaced affirmative action. . .

Talented 20: 400-1,200 minorities

. . . there could be a net loss of 1,600 minority students.

Loss of minorities: 800-1,600

SOURCES: Florida Board of Regents, Office of Gov. Jeb Bush

CAPTION: Florida Gov. Jeb Bush (R).