Ever since the start of the current congressional session, Democrats and Republicans have known they would, once again, have to confront the issue of campaign finance reform.

In the Senate, the topic is, and has been for some years, high on the agenda of both Democratic leader George Mitchell and Republican leader Robert Dole.Although they share the concern over the present system of financing Senate and House races, they have never been able to find a common solution.

Lengthy discussions between the leaders and others from both parties failed to produce an accord last year. They and their staffs are back at the table.

Now, however, Sen. Mitch McConnell, R-Ky., nominally the main sponsor of the GOP plan, is off on his own very strange side trip.

When the Senate considered the annual budget resolution last week, McConnell offered an amendment to eliminate the income tax checkoff that has financed the presidential elections in recent years.

This system, created in the aftermath of the Watergate scandal, allows taxpayers to designate $1 of their taxes for the presidential campaigns and it brings in more than $30 million a year.

McConnell, who finds the system repugnant, presented the amendment in less than honorable terms.

McConnell didn't directly propose ending public financing of the presidential elections.

He would have, however, achieved the same end by requiring that the checkoff money go to feed hungry kids - making the amendment more difficult to oppose.

True, the presidential fund has some problems.

First off, it is in dire financial straits. That stems from the problem that $1 does not buy politically, or anywhere else, what it bought 15 years ago. No one has proposed increasing the amount.

Perhaps even more resposible is the failure of the political parties to mount any kind of campaign in recent years to convince more taxpayers that it is $1 well spent.

And there is a natural recoil when some of the money goes to candidates like Lyndon LaRouche, Lenora Fulani and others who certainly are not very serious prospects for the White House.

The system may need fixing. It doesn't need killing. It does, to some extent, keep the fat cats' claws out of the race.

What makes McConnell's amendment even more bizarre is that the presidential candidates of both parties have used the fund to finance their campaigns - from the primaries to the White House. Ronald Reagan did; so did George Bush.

Even closer to home, the Senate and House abound with past and probably future White House aspirants.

McConnell withdrew the amendment, sparing the Senate a vote on the issue, but it would be interesting how the presidential candidates of the past and those of the future would vote.