It’s widely understood that the prospects for getting any kind of significant climate change legislation through Congress remain bleak, as long as the Tea Partyers and chronic reality deniers retain their grip on the House of Representatives. But there are several big steps that President Obama can take in his State of the Union speech tonight that could matter a great deal. My expectation is that he will take them.

First, environmental advocates are hoping that Obama will forcefully declare that if Congress doesn’t act on climate change, he will — by executive action. The main goal of advocates is that the Environmental Protection Agency crack down on emissions from existing power plants, and to finalize regulations on new plants (a process that’s already underway).

It appears Obama will not directly mention the crackdown on existing plants. But a decision on that is imminent. If Obama signals bluntly that he will do everything he can with his executive authority to combat climate change in the face of Congressional dithering, it will signal where he’s headed on that crucial question — and more broadly it will cheer advocates who believe Obama can singlehandedly put a dent in the problem. (Dave Roberts has a good explainer as to what Obama can do by executive action right here.)

Tiernan Sittenfeld, a senior vice president at the League of Conservation Voters, tells me that such a message from Obama would be received as a direct challenge to Congress: “If you’re not going to pass a bill to address climate change, then I’m going to use the authority I have under the Clean Air Act to first and foremost cut carbon pollution from power plants.”

The second thing Obama can do tonight is use this extremely high profile speech to draw a vivid and dramatic connection between weather volatility and climate change. Obama already took a first stab at this in his Inaugural Address, which has whetted the appetite of the environmental community for something even bigger during tonight’s prime time speech.

“It’s becoming painfully apparent that we’re experiencing the impacts of climate change in a more severe way much sooner than scientists predicted,” Sittenfeld says. “It’s important to hear the president acknowledge this and call for action. It sends the message from the very top that his administration is committed to solving this problem by using all the tools at his disposal.”

As Steve Stromberg recently noted, “in his first term the president treated global warming as an afterthought, and as recently as last November left little reason to think that he will do much more in his second term.” That began to change with the Inaugural, and I’m optimistic we’ll hear more of the right things tonight.

A strong stand on these points would also be good politics. Obama is increasingly reshaping the national debate around the priorities of the majority coalition that lifted him to reelection. This ascendant coalition — college educated whites, especially women; the millenial generation; and minorities — will likely be increasingly relied upon by the Democratic Party in the future. As David Axelrod noted recently, speaking to their priorities could help cement this coalition’s identification with the Democratic Party. Climate change is one of the priorities shared by these core groups.

What’s more, provoking opposition from Republicans to combating climate change could deepen the GOP’s estrangement from these growing segments of the electorate and fuel the sense that the GOP is increasingly trapped in the past and ideologically constrained from tackling the most urgent problems facing the country.

Greg Sargent writes The Plum Line blog, a reported opinion blog with a liberal slant -- what you might call “opinionated reporting” from the left.