Treasury Secretary Robert Rubin will announce his resignation later today, according to White House officials. They said that Pres. Clinton planned to nominate Lawrence Summers, now Treasury deputy secretary, to replace Rubin. Stuart Eizenstat, the State Department’s undersecretary for business and economic affairs, is expected to move into Summers’s current slot. Summers has been widely viewed by environmentalists as a roadblock in the Clinton administration to more progressive environmental policies. Eizenstat was the last-minute replacement as top negotiator for the administration during the high-tension talks in Japan that produced the Kyoto Protocol to reduce greenhouse gas emissions.