ST. PAUL, Minn. — Alaska Governor Sarah Palin prepares to cast herself as an outsider and take a swipe at Senator Obama today in what is the most anticipated speech of the Republican National Convention. She will pledge that as Senator McCain’s running mate, she wants to go to Washington not to seek the media’s approval but “to serve the people of this country.”

Depicting herself as “just your average hockey mom,” Mrs. Palin described her political career as mayor of her small town before her election as governor.

“Since our opponents in this presidential election seem to look down on that experience, let me explain to them what the job involves,” Mrs. Palin said in excerpts of her remarks, released in advance of her appearance. “I guess a small-town mayor is sort of like a ‘community organizer,’ except that you have actual responsibilities.”

Mrs. Palin didn’t mention Mr. Obama by name but her target was obvious: Mr. Obama began his political life as a community organizer.

Mrs. Palin also said she was not part of the permanent “Washington elite.” She said some in the media think that makes her unqualified.

“Here’s a little news flash for all those reporters and commentators: I’m not going to Washington to seek their good opinion — I’m going to Washington to serve the people of the country,” Mrs. Palin said.

The speech was the first-term Alaska governor’s first chance to fully introduce and define herself to the American public.

“Here’s how I look at the choice Americans face in this election,” she said. “In politics, there are some candidates who use change to promote their careers. And then there are those like John McCain, who use their careers to promote change.” It was another indirect dig at the Democratic presidential nominee.

In what was clearly the most important speech in her life, Mrs. Palin went over her experience as a public servant. “I had the privilege of living most of my life in a small town. I was just your average hockey mom, and signed up for the PTA because I wanted to make my kids’ public education better,” she said.

“When I ran for city council, I didn’t need focus groups and voter profiles because I knew those voters, and knew their families, too,” she said.

In the excerpts released by the McCain campaign, Mrs. Palin emphasized energy policy, one of her areas of expertise.

“Our opponents say, again and again, that drilling will not solve all of America’s energy problems — as if we all didn’t know that already. But the fact that drilling won’t solve every problem is no excuse to do nothing at all,” she said.

Mrs. Palin has been an aggressive advocate for drilling in Alaska’s Arctic National Wildlife Refuge, while Mr. McCain opposes drilling there. That difference was not touched on in the excerpts.

Mrs. Palin said that in a McCain-Palin administration “we’re going to lay more pipelines, build more nuclear plants, create jobs with clean coal, and move forward on solar, wind, geothermal, and other alternative sources. We need American energy resources, brought to you by American ingenuity, and produced by American workers.