House Democrats say they plan to send legislation expanding a children’s health insurance program to President Bush later Tuesday, expecting him to veto it within hours. But an override vote might not come for days or weeks.

Democratic leaders said they might delay a showdown to allow pressure to build on House Republicans who oppose the legislation. Labor unions and religious groups announced campaigns to encourage GOP members to vote for an override.

“We’re going to send him this bill today, and the right thing to do is for him to sign it,” said Majority Leader H. Steny Hoyer, D-Md. He offered no date for an override vote.

“Maybe next week. Maybe the week after. There’s no time limit,” Hoyer said.

The Senate cleared the bill (HR 976) last week by a veto-proof majority, 67-29, even with two Democrats absent. So the focus of Democrats’ override strategy is the House, where the bill passed Sept. 25, 265-159, short of the two-thirds majority needed for a veto override.

The measure would expand the State Children’s Health Insurance Program, or SCHIP, by $35 billion over the next five years, to $60 billion. The expansion would be paid for with tobacco tax increases, including a 61-cent increase in the cigarette tax, to $1 per pack.

Bush has said he will veto the measure, calling it excessive both in its cost and its policy.