Obama at G20 in Mexico, Romney still on the bus, plus more to watch for Monday in politics

— -- President Barack Obama is in Los Cabos, Mexico, for the two-day G20 Summit. The Greek election and the European debt crisis are certain to dominate discussions. Obama's Monday agenda includes meetings with Mexico President Felipe Calderon and Russia President Vladimir Putin.

Mitt Romney is on day four of his five-day, six-state "Believe in America: Every Town Counts" bus tour. He'll be in Wisconsin and Iowa on Monday. The tour ends Tuesday in Michigan. The bus already has made stops in New Hampshire, Pennsylvania and Ohio. Obama won all six states in 2008. ( Holly Bailey, Yahoo! News Senior Political Reporter, is covering the tour.)

Romney is not the only one on the bus. The Democratic National Committee's "Romney Economics: The Middle Class Under the Bus" tour continues Monday with events in Grand Rapids, Lansing, and Detroit, Mich., and Catholic Sisters begins a nine-state bus tour highlighting the organization's work to help people at the economic margins and targeting budget cuts proposed by Republican Rep. Paul Ryan. The "Nuns on the Bus: Nuns Drive for Faith, Family and Fairness" will make stops in Wisconsin, Illinois, Indiana, Michigan, Ohio, Pennsylvania, Iowa, Maryland and Virginia.

Meanwhile, much of  the buzz in Washington is focused on when the Supreme Court will rule on health care reform. The decision could come as early as this morning.

And then there is this: First lady Michelle Obama appears on "LIVE! With Kelly." She's on the show to promote her book, "American Grown: The Story of the White House Kitchen Garden and Gardens Across America." The show also features "Iron Chef" Marc Forgoine, who takes on the "LIVE's White House Garden Challenge" by preparing a meal on-the-spot using vegetables straight from the White House Garden.

Sources: Yahoo! News, Associated Press.