WASHINGTON  The Obama administration will begin a drive this week to expel Pepsi, French fries and Snickers bars from the nation’s schools in hopes of reducing the number of children who get fat during their school years.

In legislation, soon to be introduced, candy and sugary beverages would be banned and many schools would be required to offer more nutritious fare.

To that end, Agriculture Secretary Tom Vilsack will deliver a speech Monday at the National Press Club in which he will insist, according to excerpts provided to The Times, that any vending machines that remain in schools be “filled with nutritious offerings to make the healthy choice the easy choice for our nation’s children.”

The first lady, Michelle Obama, said last month that she would lead an initiative to reduce childhood obesity, and her involvement “shows the importance all of us place on this issue,” Mr. Vilsack said.