This is literally the opposite of what has been happening. The Dems keep moving right, and giving up voters on the Left. Every election they scream about the Leftists voter base that is both:

• A) To small to cater to
• B) So large, as to be able to swing elections

And their strategy isn't because they can't get Leftist voters, it's because they'd rather let the Republicans win, then enact Leftist policy.