Sen. David Boren's campaign finance bill is expected to come up for debate and a vote during the first week of December. Taken by itself, the Boren bill would cause as many problems as it would solve. But if the Oklahoma Democrat's ideas are joined with some other good ones on tax credits and political parties, Congress just might end up with a politically feasible package that would improve elections in this country.

Boren and his cosponsors believe candidates depend too much on political action committees (PACs) for their campaign contributions. Their solution is to limit how much candidates can accept from all PACs combined. Assuming both a primary and general election, the bill would limit House candidates to $125,000 in PAC receipts and Senate candidates to between $200,000 and $750,000, depending on the size of their state. The figures are close to the present average for the House, but would prevent further growth. (The bill does not have a cost-of-living escalator.) Senate races would be put on an immediate financial diet.

The bill has an obvious appeal. Almost nobody likes how much some candidates depend on PACs for campaign money. I am skeptical that the bill will reduce dependence as much as the sponsors say, but let us assume that it does. To achieve this result, the Boren bill would leave equally serious problems in its wake. These must be identified before Congress can think about corrections.

Why do I think that the bill will not achieve its stated objective? Because any limit on PACS will stimulate well organized groups to form ad hoc independent expenditure committees in competitive districts or states. The bill tries to address independent spending with a constitutionally dubious provision requiring broadcasters to give free time to attacked candidates. Even if the limit on broadcasters slips by the Supreme Court, however, there is no way Congress can stop groups from spending unlimited amounts on telephoning, mailing or other activities. If this happens, and PACs end up going around the campaigns, the bill paradoxically may end up making elections more dependent on the strategies of large and well-organized PACs instead of less.

Let us go along with the sponsors, though, and assume the bill would cut the role of PACs. How would the lost money be replaced? The Boren bill would work most heavily against PAC money that comes to a campaign late. But late money -- crucial in a close race -- cannot possibly be raised in small contributions.

Without late money, underdogs cannot buy advertising for the final push against a front-runner. The underdog cannot hoard money, because the underdog has to work hard to reach the point where late spending might even make a difference. But this bill would dry up the one source of money the law still allows for large, last-minute gifts. About the only people who could raise large amounts late, therefore, would be rich candidates who are willing to open their personal checkbooks.

To top it off, the candidates catching up during a campaign's final days are much more likely to be challengers than incumbents. The bill as it stands, therefore, unintentionally turns out to be a Rich People's, Independent Spenders' and Incumbents' Protection Act.

There is a way out of this box. If the main problem is that a PAC limit would dry up needed funds, the solution is to find replacement money. Ordinary public financing would not do the job because matching funds could not supply late money, and because most public financing bills include spending limits that favor incumbents. But two other approaches will work, if they are joined.

The first is to loosen up the limits on political parties. It would clearly be healthier if candidates relied more on parties than on PACs for late money. Unfortunately, the Republicans have a financial advantage over Democrats now, and Boren has said he would kill his own bill if a party amendment were added to it. I assume he reasons it would be better to help rich candidates and incumbents than give the other party a fund-raising edge.

Instead of threatening to pull the bill, it would be more sensible for Boren to see the Republicans and raise them one. Boren should think about accepting a party amendment if the GOP will adopt one promoted by the House Democratic Study Group: a 100 percent tax credit for individuals who give small contributions to candidates from their own state.

The Democratic Study Group bill would change the mix of contributions more than any other single approach I can imagine. Unfortunately, the odds against ever passing a 100 percent tax credit will go up unless Congress moves quickly. The House Ways and Means Committee removed the xisiting 50 percent credit in its version of tax reform. Today's broad 50 percent credit does little to stimulate giving and does not deserve to be law. A targeted 100 percent credit is a revenue-neutral replacement for the existing law.

So the Boren bill can be looked at two ways: by itself, or as part of a package. By itself, the bill would limit PAC receipts, decrease the supply of late campaign money and stimulate independent expenditures -- a clear formula for trouble. A package could limit PAC receipts, stimulate small givers and make candidates depend more on their parties. That would be a bill worth supporting.