Renegade Republicans today struck a tentative deal with House leaders to pass a tax cut promised in theGOP "Contract With America."With a tax vote slated for Wednesday, Majority Leader Dick Armey (R-Tex.) predicted passage of a $500-per-child tax credit for families making up to $200,000 a year. But some lawmakers warned that the compromise may not hold because a number of GOP holdouts still want to scale back the tax credit, while another group wants to increase the contributions that federal workers make into their own retirement funds. "We don't yet have 218 votes lined up, but we're making good progress," said Tony Blankley, spokesman for House Speaker Newt Gingrich. Under the compromise legislation, the tax cuts would not go into effect until after Congress passes a plan to balance the federal budget. The bill also would include a repeal of increased taxes onSocial Security benefitsand cut the capital gains tax.