Republican presidential nominee Sen. John McCain enters tonight’s third and final face-off with Democratic opponent Sen. Barack Obama trailing in the polls and looking for a performance that could change the dynamics of the race, analysts said Wednesday.

According to recent polling averages, McCain trails Obama by eight points nationally and in many of the key battleground states as Election Day looms less than three weeks away.

The Arizona senator is expected during the debate to highlight his new economic plan unveiled Tuesday that he says helps the unemployed and senior citizens by increasing retirement options and benefits.

The debate, to be held at New York’s Hofstra University and moderated by CBS News’ Bob Shieffer, gives the campaign a chance to set the tone for the remainder of the campaign, Mark Shields said Wednesday night.

“[McCain] has to have a theme tonight from this debate that carries him for the next two weeks. He can’t be retooling come next Thursday or retooling again this weekend,” he said.

Judy Woodruff said that was what she was hearing from her reporting this week in New Mexico.

“We’re all going to be looking at John McCain tonight to see how does he change the game, what is the message, what is the new idea that he’s going to put forward that is going to change the momentum because right now, to the extent we pay attention to any polls, the momentum is clearly with Sen. Obama,” Judy Woodruff said ahead of the debate.

Obama will look to avoid any major gaffes during Wednesday’s meeting. Officials with the Illinois senator’s campaign said he would focus on his own economic plan outlined on Monday that aims to helping struggling homeowners and the middle class.

“[Obama’s] like a golfer. It’s the 17th hole. He’s up by six strokes,” David Brooks said ahead of the clash. “Hit it in the middle of the fairway; lay it up before the green; putt it in; go for par. And he’ll be fine.”

New Mexico Gov. Bill Richardson told the NewsHour at the scene of the debate, “He needs to do what his done in they past two debates. Show his bi-partisan approach, show he can stay cool, not be erratic, and talk about the economy, the economy, the economy.”

The 90-minute debate, which will be focused on domestic issues, will allow both candidates to address specific questions on the country’s current financial crisis, and moderator Shieffer says he will keep the candidates on topic.

“It will not embarrass me, if they go off in a different direction, to say, ‘excuse me, could you focus on the question that I just asked?’” he told CNN.

Shieffer will be looking for the candidates to answer questions on policy decisions directly, in contrast with wider talking points that have been featured in previous debates.

“By now we’ve heard all their talking points,” Shieffer said, according to the Associated Press. “We’ve heard the general outlines of what they are talking about. The time has come to be a little more specific.”

Wednesday night’s debate, unlike the two previous debates, will have the two candidates sitting at one table and facing each other.