Associated Press: The Obama administration proposed Tuesday a new rule to tighten restrictions on pollution from coal-burning power plants in the eastern half of the country, a key step to cut emissions that cause smog. The Environmental Protection Agency said the new rule represented its most consequential effort yet to tackle pollution that contributes to smog and soot that hangs over more than half the country. The rule would cost nearly $3 billion a year, costs that are likely to be passed along to …