Barack Obama’s attempt to put school students on a carbohydrate diet has been blocked by the Senate.

The US president’s proposal to limit the amount of potatoes – namely French fries – and other starchy vegetables to two servings a week, was blocked in an amendment by the lawmakers.

US government health officials argue pupils should have more diverse diets, because they get enough spuds already.

But opponents of the proposal argue that potatoes can be a source of fibre and potassium.

They also say that potatoes and other vegetables are a cheaper and nutritious way to feed children when schools are strapped for cash.

Besides that, the government should not be dictating what children put in their mouths, the Republicans argue.

“This proposed rule would have imposed significant and needless costs on our nation’s school districts at a time when they can least afford it,” Susan Collins, a Republican senator from Maine.

The government’s proposal has angered US potato growers and members of Congress from potato-growing states.

But Margo Wootan, director of nutrition policy at the advocacy group Center for Science in the Public Interest, which pushed for the change, tried to counter the backlash.

“USDA’s proposal was about helping kids to eat a very wide variety of vegetables and I think that point has been lost in all this.

“Other vegetables have a hard time competing with potatoes,” she said.