WASHINGTON (CNN) -- President Bush on Wednesday vetoed legislation expanding a children's health insurance program by $35 billion over five years.

Kids pull wagons full of petitions this week asking President Bush not to veto insurance legislation.

Bush exercised the veto at 10 a.m. ET before leaving the White House for a trip to Lancaster, Pennsylvania, to discuss the federal budget and taxes.

Speaking in Pennsylvania, Bush said he vetoed the bill because it was a step toward "federalizing" medicine and inappropriately expanded the program beyond its focus on helping poor children.

"I believe in private medicine, not the federal government running the health care system. I do want Republicans and Democrats to come together to support a bill that focuses on the poorer children," the president said, adding the government's policy should be to help people find private insurance.

Democrats quickly took to the floors of the Senate and House of Representatives to condemn the veto of the bill that received bipartisan support.

here are a few reasons the SCHIP program is so important :

*12% of American Children don't have any insurance coverage at all
* The U.S. Ranks 37th in the world for infant mortality
* One-in-five U.S. jobs does not provide health insurance, a pension, or wages high enough to support a family
* For a family of 4, one year of health insurance costs an average of 11,000
* Over 1/2 of all bankruptcy filings in 2001 were a result of medical expenses