Albert A. Spiegel, a longtime supporter of President Reagan who served for the past two years as a presidential adviser on matters of concern to the Jewish community, abruptly left his unofficial post yesterday.

Spiegel declined to discuss the reasons for his decision. But he acknowledged that it had to do "in part" with an article in The Wall Street Journal yesterday morning about the Middle East.

The article included a report that Reagan is alleged to have told Jordan's King Hussein that he knows he is going to lose the Jewish vote in 1984 by pressing a Mideast peace plan that Israel opposes, but that the president felt he could win reelection without that bloc of votes.

Senior Reagan administration officials said privately yesterday that it was The Wall Street Journal article that upset Spiegel to the degree that he left his unofficial administration post. But these officials denied that Reagan had said anything to Hussein about "the Jewish vote." Reagan, one of them said, "has never said anything like that and anyone who knows the president would find that out of character." The officials also denied that Reagan had told the Jordanian monarch that they would be working together for another six years, a remark that would have suggested that Reagan had decided to seek another term.

Spiegel is a Los Angeles businessman who began working in Reagan's campaigns for governor of California in 1967 and served as a vice chairman of his 1980 presidential campaign. Because Spiegel also served as the national chairman of the Reagan presidential campaign in the Jewish community, his departure could stir considerable concern in that constituency.

Spiegel said that aside from the news report, there were other "procedural as well as programmatic" reasons for his decision to terminate his association with the White House.

But he declined to be any more specific, saying that he "had and hope to still have a cordial relationship" with the president, who he said he "admires and respects."

Spiegel, who shared an office in the Old Executive Office Building, stressed that he did not have a formal position in the administration, that he served as a volunteer and thus he could not formally resign. Rather, as he phrased it, "I decided I would no longer continue in that capacity."

President Carter's first adviser on relations with the Jewish community, Mark A. Siegel, resigned at virtually the same point in the Carter administration as Spiegel left the Reagan administration. Siegel cited disagreements with the President Carter'sMiddle East policy.

Siegel, who had served in a paid position as a deputy assistant to the president, later went to work for the presidential campaign of Sen. Edward M. Kennedy (D-Mass.).