WASHINGTON -- Americans go to the polls Tuesday to decide control of the U.S. Congress for the next two years and to pick governors for 36 of the nation's 50 states.


President Bill Clinton is not on the mid-term ballot. But his political strength and ability to pass promised legislative programs are at stake, as Democrats struggle to keep majorities in the Senate and House of Representatives.


Republicans and most impartial analysts are predicting big gains if not an outright takeover by Clinton's opponents in both houses of Congress and in statehouses across the land.


Losses by the party in power are common in non-presidential elections, but polls show unusual frustration and anger aimed at Washington, with a sense that Clinton and his party have failed on domestic issues.


Democratic strategists insist, however, that Clinton's foreign policy successes, hard campaigning by incumbents and a generally robust economy are turning the tide their way in the last days before the vote.


Although there is no national ballot, some campaigns around the country are attracting national and international attention, including a California referendum that would halt state services for illegal immigrants.


Sons of former Republican President George Bush are running strong races against Democratic incumbents in Florida and Texas.


At least two men once convicted of crimes are on the ballot: Iran-Contra figure Oliver North, whose convictions were overturned, is aiming to be a member of the Senate he once lied to, and Marion Barry is considered sure to return as mayor of the nation's capital where he was caught on videotape using cocaine.


In Washington, Tom Foley, the powerful House speaker, is fighting for his political life against Republican lawyer George Nethercutt, while in Massachusetts, longtime senator Edward Kennedy is running his closest race yet against businessman Mitt Romney


In an election marked by record spending, tough negative advertising and widespread discontent with government, more than 125 million citizens are registered to vote. But if low voting trends continue, only about 60 percent of those registered, will actually cast ballots.


Polls indicate a close fight for control of the Senate, where Democrats now hold a 56-44 majority. If Republicans win all 19 races where they were leading in the polls this week, the breakdown of the new Senate would be 50-50, with Vice President Al Gore holding the deciding vote. Only a third of the Senate goes up for election in general elections held every two years.


All 435 seats in the House are on the ballot, although 37 members are unopposed.


Democrats, who have controlled the House for four decades, are confident of keeping a majority, but Republicans expect big gains in open seats where incumbents are not running. Democrats now hold a 258-176 majority in the House, with one independent.


Big Republican gains, even if the party does not get an absolute majority in either House, will make it more difficult for Clinton to pass key legislation such as health care reform. He has had trouble getting unanimous support from his own party on many issues.


The gubernatorial races are less important to Clinton, but could have significance as he tries to gather support for re-election.