One State=One Vote

[Erc]

Interestingly enough, the only elections in the last century where this would have made a difference would be 1976 and 1960, buth very close elections (with no clear PV winner in the latter).

[Erc]

Generally, since the 23rd Amendment, such a condition would require the Democrat to win around 51.5% of the two-way vote in order to win a majority of the states [ranging from a low of 50.2% in 1976 to a high of 52.1% in 2000, ignoring 1968].  A nice bias to the Republicans, though not massive.  (Though, if it were in place, it would all but guarantee a McCain victory this year).

"Tipping Point" states for a 26-state majority:

2004:
Florida.  Kerry would have needed 51.3% of the two-way vote to win here (he won 48.6%).

2000:
Nevada.  Gore needed 52.1% nationwide (he won 50.3%)

1996:
Ohio.  Clinton needed 51.1% nationwide (he won 54.7%)

1992:
Tennessee.  Clinton needed 50.9% nationwide (he won 53.5%)

1988:
Maine.  Dukakis needed 51.9% (he won 46.1%)

1984:
Connecticut.  Mondale needed 51.8% (he won 40.8%)

1980:
Oregon.  Carter needed 50.2% (he won 44.7%)

1976:
Maine.  Carter needed 51.4% (he won 51.1%)--barely losing the count here, Maine and Oregon making the difference here.

1972:
Vermont.  McGovern needed 51.4% (he won 38.2%).

1968:
Complicated, due to Wallace...
To Prevent a Nixon Majority:
Wisconsin.  Humphrey needed 51.6% of the two-way vote nationwide to win here, but only won 49.6%.

To Win an outright Majority:
Nevada.  Humphrey needed 54.3% (he only won 49.6%).

1964:
Delaware.  Johnson needed 50.2% of the two-way vote nationwide (he won 61.3%).

[Erc]

Compare that to the Electoral College "Tipping Points" (for the past 20 years):

2004:
Ohio: Kerry needed 49.81% of the two-way vote nationwide to win here (he won 48.76%).

2000:
Florida: Gore needed 50.273% nationwide (he won 50.268%).

1996:
Pennsylvania: Clinton needed 49.57% of the two-way vote (he won 54.74%).

1992
Colorado: Clinton needed 50.65% of the two-way vote (he won 53.45%).

1988
Michigan: Dukakis needed 50.08% of the two-way vote (he won 46.10%)