FiveThirtyEight: “On Tuesday, we’ll get a taste of whether Democrats’ electoral advantage on paper will hold up in practice, as California and Wisconsin hold special elections for two vacant congressional seats.”

“The main event is in the California 25th Congressional District, a bellwether seat in the north Los Angeles suburbs, where both parties see a chance to add to their ranks in the House. But if Democrats are also competitive in the quickly reddening, rural Wisconsin 7th Congressional District, it could signal another blue wave in the fall.”

Related: The political calendar has been updated.