Mitch McConnell has decided to wager the Republican majority in the Senate on blocking Barack Obama’s pick for the Supreme Court.

It’s a bold and understandable gambit designed to prevent a leftward lurch in jurisprudence after Antonin Scalia’s unexpected death this weekend, but it could backfire badly.

Assuming the president picks a Hispanic, African American or Asian American – bonus points if she’s a woman – this could be exactly what Democrats need to re-activate the Obama coalition that fueled his victories in 2008 and 2012. Even if he does not go with a minority candidate, the cases on the docket will galvanize voters who are traditionally less likely to turn out.