Democrats and health care interest groups will strike back with an intense two-week campaign loaded with big time advertising and private arm twisting.

To override Bush's veto, they need to convince about 15 more House Republicans to vote for the reauthorization of the Children's Health Insurance Program, known as CHIP.

"It will not be easy but we are making every effort," said Stacey Farner Bernards, spokeswoman for House Majority Leader Steny Hoyer.

The veto override vote is expected to take place on Oct. 17. The Senate has enough votes to overturn the veto, but won't take a vote until the House acts.

Bush has only used the veto - his ultimate legislative weapon - three other times. And more times than not, Sen. Orrin Hatch, R-Utah, has stood against president.

Hatch agreed with Bush when he vetoed a bill that would have led to a pullout of Iraq. But Hatch opposed the president when he twice vetoed a bill that would have expanded stem cell research.

Hatch is also one of the biggest backers of CHIP. He has repeatedly attempted to knock down the president's objections saying the president has been given bad advice and has misconstrued what the bill actually does.

On Wednesday, Hatch went even further calling CHIP "the morally right thing to do."

"I hope that we can muster enough votes to overturn this veto," he said.

CHIP provides health insurance to children in families that are too wealthy for Medicaid but too poor to buy private coverage. The program is run independently by each state with a mix of state and federal dollars.

Currently, 6.6 million children are receiving coverage. Congress overwhelmingly passed an extension that would bring the spending from $25 billion to $60 billion over the next five years, with the hope of covering a total of 10 million children.

Bush objects to the bill saying the price tag is too high, it relies on a tax increase and the expansion may encourage families to drop private coverage in favor of this public program.