Despite what have seemed unbridgeable differences over how and when to balance the federal budget,President Clintonand Republican leaders today predicted thata compromise can be reached this summer. "We have major differences over how the budget ought to be balanced," the President said after meeting withSenate Majority Leader Bob Dole, House Speaker Newt Gingrich and Democratic leaders. "But I think it would be an error to delay it and run the risk of having a crisis in government." Dole and Gingrich made no pledge to budge, but Sen. Thad Cochran (R-Miss.), chairman of the Senate Republican Conference, said both parties "are committed to making this work."