THE recent gust of tax-cutting proposals heralds the presidential campaign season just ahead. With polls showing deepening concerns about a weak economy, Republicans and Democrats want to show they care.Both camps are banking on the popularity of tax cuts - versus the kind of stimulative federal spending that used to be part of the formula for overcoming economic inertia. "Big spender" is a label no one wants. But beyond that, last year's bipartisan budget agreement ruled out new spending programs without new taxes, or new trims, to cover them. One Democratic tax-cutting plan, put forward by Senate Finance Committee chairman Lloyd Bentsen, appeals to middle-income voters. It includes a $300 tax credit for each child in a family. The cost to the federal treasury would be offset by cuts in defense spending. Would the Bentsen plan give the economy an immediate boost, putting extra money into the hands of consumers? Not likely. Since the chances of quick action on major tax legislation are slim, a stimulative effect would click in only way down the line. Beyond that, families these days seem more intent on paying off old debts than acquiring new ones with big-ticket purchases. The White House plan will again put forward a capital-gains-tax cut as the centerpiece of a "pro-growth" package. Will this quicken the economy, giving wealthy Americans added incentive to invest? It's an article of faith with supply-side Republicans, but many economists have their doubts. There's no doubt, however, that Democrats will leap at the chance to blast President Bush for again offering "tax breaks for the rich." Politics aside, what about the immediate needs of the economy? The Federal Reserve is best able to respond. It has lowered interest rates a bit in recent weeks, with little effect as yet. It should keep trying.