By Mark Willen, Senior Political Editor July 17, 2008 Rhodes Cook, a political pundit and former colleague who has made a career of explaining the present by studying the past and the statistical trends, has just published a new analysis of recent voter registration figures. It's not likely to comfort many Republicans. To see if the electoral map is really changing, Cook mapped the changes in voter registration statistics. He found that across the nation, Democrats have gained 700,000 new party members since President Bush's re-election in 2004, while Republicans have lost 1 million -- and that's only in the 29 states that register by party. The numbers strongly suggest that several states won by Bush will be up for grabs this year. Consider Iowa, a state Bush won by 10,000 votes in 2004. Democrats have increased their numbers by 68,000 since then, while Republicans have added only 7,000. In Nevada, which went for Bush by 21,500 votes, Democrats have added 16,000 while Republicans have lost 44,000. Democrats are also solidifying their lead in states that John Kerry won four years ago. In Oregon, which went Democratic by 76,000 votes in 2004, Democrats have added 32,000 while Republicans have lost 92,000. In California, Democrats have added more than 300,000 while Republicans have added just 15,000. Not all states register by party, but Cook has all the data for those that do, as well as the historical change.