WASHINGTON — A bipartisan group of senators has largely agreed on a broad immigration bill that would require tough border measures to be in place before illegal immigrants could take the first steps to become American citizens, according to several people familiar with drafts of the legislation.

But in a delicate compromise worked out over weeks of negotiations, the bill does not impose any specific measurements of border enforcement results that, if they were not met, would stop the immigrants from proceeding toward citizenship.

Instead, the bill allows a period of 10 years for the Department of Homeland Security to make plans and use resources to fortify enforcement at the borders and elsewhere within the country before it sets several broader hurdles that could derail the immigrants’ progress toward citizenship if they are not achieved.

During the first decade after passage, the bill sets ambitious goals for border authorities — including continuous surveillance of 100 percent of the United States border and 90 percent effectiveness of enforcement in several high-risk sectors — and for other workplace and visa enforcement measures. It provides at least $3 billion for Homeland Security officials to meet those goals during the first five years, with a possibility of additional financing.