Washington — Because of his continuing popularity, President Reagan still has time to pull out of his current performance-rating dip and put together a successful four years in office.
''Never, never underestimate Ronald Reagan,'' says Democratic national chairman Charles Manatt. ''He's in a sophomore period now. You can't count him out in any remote sense of the word.''
Mr. Manatt is a leading critic of the President. He thinks Mr. Reagan's ''conservative ideological impact'' is wearing out. And he cites national polls that show the President's job rating dropping to the low 40 percent range. But he concedes that the Democratic Party's own polls show that 30 to 40 percent of those who fault the President's performance say they still like him.
Interviews with state Democratic leaders in all geographical regions of the US yields the same assessment: a President who faces growing criticism but who, at the same time, maintains the popularity and trust that permits him to remain effective.
State Democratic chieftains are quite critical of the President. And they appear to see the President's decline in the polls as promising for Democratic prospects next fall. But invariably, these leaders concede - without much relish - that Reagan still commands personal affection and trust. This makes him a potent force.
Says Richard Boyer, New Hampshire Democratic state chairman: ''He (Reagan) is a decent human being, a nice fellow. That's the thing that keeps him going.''
''The thing that holds him up is his popularity,'' says Boyer. ''People want to give him the benefit of the doubt. Even Democratic leaders feel that way. The country is in such bad shape. And he's the President.''
Boyer adds: ''Unfortunately Reagan has a myopic view of what needs to be done.''
Pat Lea, Missouri state chairman, says, ''People still like him. But they are very disappointed in his performance. But they do feel he is an honest person.''
Says Arline Bidwell, Democratic national committeewoman for Connecticut, ''He's still popular as a man. A popular person. He has a popular appearance. But there's a growing disenchantment with his program.''
These comments jibe with a new Los Angeles Times-Cable News Network survey that shows that Americans appear willing to continue to give the President and his policies a chance to put the economy back in shape. An overwhelming majority of those polled blamed the economy's distress on former administrations. Even those who voted for President Carter in 1980 tended to follow this pattern.
The Democratic chieftains contacted by the Monitor said that if a vote were held today Reagan would beat Carter - even though, as they see it, Reagan's support would be less than in the fall of '80. But at the same time, these leaders say Reagan's performance-rating slump, together with the current recession, signal a great opportunity for Democratic candidates next fall.
Perhaps reflective of the frustration the Democrats feel regarding the President is this comment from Hazel Evans, vice-chairman of Florida's Democratic state committee: ''I think you have a good person in Reagan - but a lousy President.''
A couple of months ago, state GOP leaders around the US said the public's patience with Reagan was running thin. But in recent conversations with these politicians, they now say support for Reagan has stabilized. His popularity is the brake. He's still in command and still has the backing he needs to get his job done.
US Commerce Secretary Malcolm Baldrige was, like Mr. Manatt, talking to reporters over breakfast when he said, ''Outside of Washington I find that people generally say they want to see Reagan's program work - and that they will give him more time. The average voter has seen 20 years of other approaches to the economy. So now they want to give the President more time.''
Special trade ambassador and former GOP national chairman, Bill Brock, talked along similar lines when meeting with this same breakfast forum recently. He emphasized that presidents usually go through a slump in the polls during their second year. And he, too, pointed out that Reagan's popularity was holding.
Reagan, himself, is said to feel that if he can keep the public's support until this summer - when he hopes to see the economy improve and interest kindled in his program - he will maintain the momentum he must have to put together a successful presidency. The President's polls indicate he probably will be able to bridge that period by trading on his popularity.
Aides say Reagan is being helped through these difficult months by the Democrats' inability to offer an alternate economic program. Says one administration official, ''This Democratic default helps the President to keep the initiative even in these rather dark days.''