WASHINGTON — Republican lawmakers opposed to expanding the children's health insurance program argued that broadening the plan would force 2.4 million children into government-sponsored insurance.

"We're going to replace a lot of private insurance with government insurance," Arizona Sen. Jon Kyl said Monday as the Senate prepared to consider a bill to extend health insurance to about 4 million uninsured children.

Kyl and other Republicans also expressed reservations about covering the children of legal immigrants under the State Children Health Insurance Program.

Overall, the Senate legislation would increase spending on the program by $31.5 billion over the next 4½ years. The expansion would be paid for by increasing the federal excise tax on tobacco products.

Republicans lack the votes to block the legislation as Democrats have strengthened their majorities in Congress. However, before the bill can be cleared and sent to President Barack Obama for his signature, Senate and House members will have to work out the differences in the legislation.

The House passed a comparable bill nearly two weeks ago by a vote of 289-139. Forty Republicans voted in favor of the measure.

In late 2007, former President George W. Bush twice vetoed Democratic-led bills to expand children's health insurance coverage. Obama has said that he hopes the Senate will act with the same sense of urgency as the House so that a bill reauthorizing and expanding SCHIP would be one of the first measures he signed into law.

Senate Majority Leader Harry Reid, D-Nev., alluded to Bush's vetoes in announcing that the Senate would take up the SCHIP bill late Monday.

"Jeopardizing the health of American children is not a political victory for anyone. It's a loss for everyone. It's long past time that we corrected it," Reid said.

Many Republicans are unhappy with the latest legislation, saying it does too little to limit the program to children of the working poor. They want stricter limits on eligibility.

Kyl said many Republicans oppose a provision, which was approved by the House, to allow states to use Medicaid or SCHIP to cover children of legal immigrants. Current law requires a five-year waiting period before legal immigrants become eligible for coverage under Medicaid and SCHIP.

The provision has a cost of about $1.3 billion over five years and would allow about 300,000 more children to participate in SCHIP after that period. Eighteen states incur the cost of health coverage for children of new legal immigrants, according to the Center on Budget and Policy Priorities, a liberal-leaning think tank.

To pay for the additional health coverage, lawmakers have proposed increasing the federal excise tax on a pack of cigarettes to $1. That's a 61-cent increase. Other tobacco products will be hit with higher taxes too. The tax increase will be comparable for chewing tobacco and pipe tobacco, but will be much steeper for roll-your-own tobacco and some cigars.