If Nader someone how won Florida, that deadlocks the electoral college.
Have him be born in Florida and have a Cuban wife. He is more populist. Both Gore and Bush make anti Cuban gaffes.
Did a thread on this once, where all states allocate proportionallyBarring faithless electors, the only way I could see Nader making a breakthrough into the Electoral College is if some *large* state decides to award its electoral votes proportionately (not by winner-takes-all and not by congressional districts--even in 2000 Nader did not get better than ten percent in any congressional district) so that Nader's getting five percent of the vote in the state (which has, say, twenty electoral votes) would get him one elector from the state. But this is very unlikely to happen--big states are jealous of the power winner-takes-all gives them.
As for what would happen, the same thing would happen as in any other election where no candidate gets a majority in the Electoral College--it goes into the House, to be decided by one-delegation-one-vote. In the actual 2000 election, this would result in Bush winning. But a country where Nader does far better than he did in OTL--and yet somehow this does not lead to an Electoral College majority for the Republican--is so different politically from the US as we know it that it is impossible to say what the composition of the House would be.
GOP controlled most state delegations, meaning President Bush, whilst Democrats had 50 Senate seats + tie-breaking vote by Gore, meaning Vice-President Lieberman.
Calculation:
Candidates who didn't get enough for 1 EV were discarded from the calculation. EVs were rounded up to the nearest whole number, and winning a state ensured said candidate would have at least one more EV than his competitor - Ohio would have split 10-10-1, but since GWB got most votes and Nader was furthest away from the votes necessary for a whole electoral vote, it split 11-10-0.