We were disappointed, however, that Mr. Obama’s address failed to insist that the best way to do all of these things is to establish a broadly based, economywide cap-and-trade system that would put a price on carbon emissions. He opened the door far too wide to alternative policies that aren’t real alternatives — and to more stalling.

A House bill approved last year would set up such a system. Action in the Senate has been delayed for months, as Republicans, and some Democrats, have argued without any real proof that capping and pricing carbon emissions would cripple the economy by driving up the cost of energy.

On Wednesday, Democratic leaders, who have promised to bring an energy bill to the Senate floor after the Fourth of July recess but are nowhere near agreement on what should be in it, will troop down to the White House. This time, Mr. Obama must stress, explicitly and emphatically, that a conventional energy bill will not do — and that attaching real costs to older, dirtier fuels now dumped free of charge into the atmosphere is the surest way to persuade American industry to develop cleaner fuels.

Mr. Obama also needs to push back a lot harder against critics who claim, wrongly, that such an approach will raise electricity and fuel prices to unacceptable levels.

A new analysis from the Environmental Protection Agency shows that the most ambitious bill before the Senate, sponsored by John Kerry and Joseph Lieberman, would cost American households at most an additional $150 a year. That does not seem too high a price to pay for helping to avoid dangerous climate change. A simpler if less ambitious carbon cap proposal offered by Senators Susan Collins, a Maine Republican, and Maria Cantwell, a Washington Democrat, is designed to cost consumers even less, and is worthy of attention.

There are other honorable bills out there that have much to recommend them but fall short because they do not include mandatory greenhouse gas reductions or a price signal. A measure sponsored by Senator Jeff Bingaman, Democrat of New Mexico, would require utilities to generate 15 percent of their power from renewable sources by 2021.

A bill from Indiana’s Richard Lugar (one of the few Republicans to have stepped forward with genuinely positive ideas) seeks tighter fuel economy standards for cars and stricter efficiency standards for buildings — two huge sources of carbon emissions.

Those are good ideas that should be part of a comprehensive bill. By themselves they are not enough to reduce the country’s dependence on fossil fuels or combat the dangers of climate change.

The politics won’t be easy. Some big oil and power companies will push back hard, as will nearly all Republicans and many Rust Belt Democrats. But Americans are rightly outraged by the spill in the gulf. This is clearly the moment for President Obama and Senate leaders to deliver a tough and ambitious energy bill capable of protecting the environment and the nation’s security.