For Democrats to continue their electoral success in 2010, they’ll have to mobilize the 10 million first-time voters who backed President-elect Obama and build on gains among higher-income, Western and suburban voters, Marc Ambinder writes. Republicans looking ahead to 2010 need to win back independents and keep the lower-income white voters who voted for the GOP last year, Ambinder adds. Democrats have built a Big Blue Wall of 18 states that they can count on every four years for 248 electoral votes, according to Ron Brownstein.