A bill that would cut taxes on dividends and capital gains for several years was approved by House and Senate negotiators and could be passed by both chambers of Congress by Friday. The measure blends the proposals of President Bush, the Senate and the House in a compromise. At $318 billion, it is smaller than any of the three constituencies initially sought. And the specifics of the cuts combine aspects of all three, as well, by incorporating the House's wish to lower both capital gains and dividend taxes and the Senate's desire for a finite time frame. Senate Majority Leader Bill Frist said after a series of negotiations with House leaders that the plan had the backing of 50 senators, allowing Vice President Dick Cheney to break the tie in a vote expected Friday. The House is scheduled to vote on the same package Thursday. The proposal would lower the tax on dividends from about 39% (at the top end) to 15%, and capital gains from about 20% to 15%, most likely through 2008. The bill's backers have repeatedly said they hope to extend the reductions past the formal 2008 reinstatement date. Among other things, the measure would give a tax break to married couples, increase the tax credit for children to $1,000 per child, and grant $20 billion in aid to fiscally strapped states. Congressional budget negotiators said Americans' income-tax rates could start falling on July 1.