Administration officials think MX will be approved

Despite major setbacks last week, administration officials are confident Congress will approve the MX missile, but concede the ''dense pack'' basing plan is in serious doubt.

Defense analysts inside and outside the administration argue that the MX is essential for national security and as a bargaining chip in arms reduction talks with the Soviet Union.

Reacting to the dense pack's defeat in the House and the disclosure that most of the Joint Chiefs of Staff opposed the plan, President Reagan said Saturday he had no objection to a vigorous congressional debate on what the MX's basing mode should be, but said it's vital to approve the weapon's production.