It is tempting to say that, with friends like these, President Reagan doesn't need Democrats.
We refer to Sen. Jesse Helms and the few other far-right Republican supporters of Mr. Reagan who filibustered against his gasoline tax legislation. The tax passed, but only after the filibuster rolled on to a point of admitted irritation at the White House and threats of political retaliation from even another conservative GOP senator.
Not that Senator Helms could be denied his defense of the filibuster as the last resort of an embattled minority. Nor was his declared championing of the ''little man'' without political merit. After all, some previous gas tax proposals had rebates to low-income drivers or other strong provisions to offset the tax's regressive nature.
But a tax-cutting President had come to accept this particular tax hike for its particular purpose of restoring the transportation infrastructure. Mr. Helms's performance was suspected by some to be as much for his electoral survival back in North Carolina as for the nation's little men. It was also seen as representing alienation from the White House on more than this issue.
Who would have thought that such a split could develop so soon between Mr. Reagan and one of his earliest and staunchest backers? Well, observers at the 1980 Republican national convention might have thought so. There Mr. Helms was looked to by the party members who were more Reaganite than Reagan.
The nomination of ''moderate'' George Bush for vice-president was only one of the episodes that dismayed these rightists. Some warned that if Ronald Reagan, too, let them down by diluting his conservatism - as Richard Nixon had done in their eyes - they would have to find someone else by 1984.
Now Mr. Helms seems to focus the concerns of those who feel Mr. Reagan has not given sufficient push to their social agenda, including the elimination of women's choice in abortion and the establishment of schools' choice in classroom prayer. In economic and foreign policy terms as well, where government centrists breathe a sigh of relief for every White House sign of moderation, the Helmsians seem to be driven a little farther up the wall.
Thus a potential for serious divisiveness in the country underlies all the joking about Senator Helms as the Grinch stealing Christmas from senators who would rather be caroling. Republican analyst Kevin Phillips is only one of the voices alerting the public to possible political strains from a ''populist conservative'' disappointment in government.
Can Senator Helms and President Reagan agree to disagree on some matters and get back to working together for common goals? They did so for a while. The answer now will depend on how the public beyond North Carolina responds to the filibuster - not to mention the tax hike - and on how advisers on both sides read that response.