Al Gore is unlikely to run again (for the Presidency). His ideas are catching on, but people still don't want to pay for them.
"Besides Mr Gore, however, no plausible candidate of either party favours a carbon tax, the most efficient way to tackle emissions. (Chris Dodd, a Democrat, does, but he surely won't win.) Voters prefer solutions that are either cheap or that they think will be paid for by someone else. A poll for the New Scientist magazine in June tried to quantify this, with sobering results. Only half of Americans would favour rules to force power companies to emit less if that raised their monthly electricity bill from $85 (the average in 2005) to $155 (an estimate of the hike needed to lower American emissions by 5% by 2020). And only 37% could stomach a tax that raised petrol (gasoline) prices to $4 a gallon. That would be an unprecedented hardship for Americans but barely half what the stuff now costs in Britain.
"This is why Mr Gore talks more bluntly now than he ever did on the campaign trail, and why no serious presidential contender echoes him. You cannot win the White House by telling Americans that they must pay more to drive, or by telling Midwestern coalminers that their industry must clean up or die. But if candidates do not prepare America for the cost of tackling climate change, the next president will have no mandate to impose it. Now that's an inconvenient truth."
(The foregoing, excerpted from The Economist, October 20, 2007, pg. 48, sums up, in my opinion, why Al Gore won't run again.)