Connecticut Democrats have stepped up pressure on Republican Gov. M. Jodi Rell to sign a health insurance bill that would open the state-employee health plan to a pool of municipalities, nonprofits and small businesses. The bill was passed by the large Democratic majorities in the House and Senate without attracting a single Republican vote. Rell's administration says that the bill's Democratic proponents exaggerate potential savings to the new pool and downplay the risk of as much as $78 million in higher costs.