The Bush administration has proposed a crack down on the aggressive marketing of private Medicare insurance plans by outlawing unsolicited visits and telephone calls to beneficiaries, regulating commissions paid to sales agents, and increasing the fines that could be imposed on insurers. Medicare beneficiaries and state officials have complained that high-pressure sales tactics led some people to sign up for unsuitable policies. After reviewing public comments on the issue, federal officials intend to implement final rules before the marketing of plans for 2009 begins in October.