Democratic leader Robert Byrd said Wednesday that the Senate can approve the INF treaty before the start of the U.S.-Soviet summit if only "legitimate and serious" amendments are offered.

Byrd said, "If a lot of other things get in the way," progress on the treaty would be impeded, cutting down prospects of passage in time for the summit, and conceded that was "likely" to happen.Although Byrd did not pinpoint Sen. Jesse Helms, the Republican North Carolina conservative has said he will offer "some dozen" amendments, which backers of the treaty consider neither legitimate nor serious. Senate Republican leader Robert Dole said he did not know of any senators, Republican or Democratic, who want to delay the historic treaty but said that amendments would be offered.

White House spokesman Howard Baker told reporters Wednesday he is hopeful that the Intermediate-Range Nuclear Forces Treaty will be ratified in time for President Reagan to take it to Moscow with him for his May 30-June 2 summit with Soviet leader Mikhail Gorbachev.

"To be able to take the ratified treaty to Moscow will be a major plus," Baker said. "It would be a disappointment, but it won't be a disaster" if it is not approved by then.

However, he said that lack of a ratified accord "might influence the Soviets not to go ahead with the next treaty," referring to the Strategic Arms Reduction Treaty with the proposed 50 percent reduction in superpower long-range missile arsenals.

Debate began on the INF treaty Tuesday with little doubt that the Senate can muster the two-thirds majority for passage, but not certain if it can be approved in time for the Moscow summit.