Here are our picks for the top local stories to start your day:

Andy Gao, 3, sits in grocery basket as his mother Anna Zheng shops in the meat department at Great Wall Supermarket. (Photo by Tracy A. Woodward/The Washington Post) (Tracy A. Woodward/THE WASHINGTON POST)

Mitt Romney won the support of 72 percent of D.C. Republicans in a straw poll Monday night. Newt Gingrich came in second with 8.7 percent, while Rick Santorum and Ron Paul each finished with about 8 percent. The District holds its primary election on April 3.

There will be extra patrols at Prince William County’s Potomac High School today, after graffiti appeared in a school bathroom that indicated a student planned to bring a weapon to school. Police say there is no evidence the threat is credible.

Coming up today on PostLocal:

— The Post’s Laura Vozzella @LVozzella will be live-tweeting and live-blogging the protests outside the Supreme Court today as oral arguments continue on a set of challenges to the sweeping 2010 health-care law.

— Health-care law expert Ilya Shapiro will join The Post at 1 p.m. for a live chat about the case, including his own thoughts on whether the health-care bill’s individual mandate requirement is unconstitutional.

— Planning to walk down the aisle soon? D.C. bridal shop owners Carine Krawiec and Julia Lichtman will be chatting at 11 a.m. about the latest wedding trends and etiquette, and will offer a dollop of their own advice on solving wedding-planning troubles.