TWASHINGTON—Hardline opponents of an auto industry bailout branded the industry a “dinosaur” whose “day of reckoning” is near, while Democrats pledged Sunday to do their best to get Detroit a slice of the $700 billion Wall Street rescue in this week’s lame-duck session of Congress.

The companies are seeking $25 billion from the financial industry bailout for emergency loans, though supporters of the aid for General Motors Corp., Ford Motor Co. and Chrysler LLC have offered to reduce the size of the rescue to win backing in Congress.

Senate Democrats intended to introduce legislation Monday attaching an auto bailout to a House-passed bill extending unemployment benefits; a vote was expected as early as Wednesday.

A White House alternative would let the car companies take $25 billion in loans previously approved to develop fuel-efficient vehicles and use the money for more immediate needs. Congressional Democrats oppose the White House plan as shortsighted.

Majority Democrats will need at least a dozen GOP votes in the Senate to prevent opponents from blocking their measure — assuming all Senate Democrats support it. Senate Republican Leader Mitch McConnell of Kentucky questioned whether there was sufficient Democratic support for an auto bailout in a statement released Sunday.

“The silence from the Democrat rank and file on this matter has been deafening,” McConnell said.

So far two Republicans publicly have voiced support for the idea. Several others, included Minnesota Sen. Norm Coleman on Sunday, have indicated they might accept a rescue under strict conditions.

Sens. Richard Shelby of Alabama and Jon Kyl of Arizona said it would be a mistake to use any of the Wall Street rescue money to prop up the automakers because a bailout would only postpone the industry’s demise.