Is Donald Trump's presidential star falling? Polls and pundits see a dip.

More than a few Republican strategists are hoping and praying that Donald Trump's 15 minutes are just about over as a potential presidential candidate.

Former Bush adviser Karl Rove has called the idea of a presidential run by the real estate mogul/reality TV star a "joke." Pollster Whit Ayres dubs him "a snake oil salesman." In private, Republicans worry that he's so good at attracting media attention, he has deprived more credible candidates of political oxygen.

But now that the Obama birth certificate issue has faded, The Donald’s poll numbers among Republican voters are fading too. In the newest major poll, by Public Policy Polling (PPP), Mr. Trump is down to 8 percent. PPP, a Democratic firm, had him at 26 percent a month ago. Overall, in the Real Clear Politics rolling average of major polls, he has slipped to third place with 13 percent among GOP voters. Former Massachusetts Gov. Mitt Romney and Arkansas Gov. Mike Huckabee are each a bit above 16 percent.

But Trump may have another five minutes left on the clock. He has promised to announce his presidential intentions (yea or nay) by June, though he will not reveal an announcement date during the two-part season finale of his show “The Celebrity Apprentice” May 15 and 22 as previously stated, Mr. Trump’s spokesman told National Journal.

"It's not inconceivable that he will make an announcement either before or after the finale, which we would clearly let you know about," spokesman Michael Cohen said Tuesday.

All of which furthers speculation that Trump's flirtation with the presidency is just a publicity stunt. But there's no doubt he remains catnip for the media. He's colorful and outspoken, and his critique of President Obama's tenure resonates with many conservatives – which gets him on TV, which keeps his name out there, which keeps him "top of mind" for some Republicans when pollsters come calling.

Trump kept the drumbeat going Wednesday in a luncheon speech at the Greater Nashua Chamber of Commerce in New Hampshire, home of the first GOP primary. “I’m thinking about running,” he reasserted, the Nashua Telegraph reported. He also floated some policy ideas, such as extracting $1.5 trillion worth of Iraq’s oil reserves to pay the US back for the cost of the war there.

At this point, it’s still early in the 2012 cycle, and the Republican field is forming slowly, at least compared with four years ago. Of the top four in the Real Clear Politics average, both Mr. Huckabee and former Alaska Gov. Sarah Palin have shown few serious signs that they actually intend to run – another reason to take these early polls with a grain of salt.

"The fact that no one consistently scores above 20 percent doesn't tell you that Trump is a leading candidate. It tells you that Republicans are very dissatisfied with their choices," says Mr. Ayres. "It tells you that this nomination battle is totally wide open, and there is an opportunity for a serious and credible candidate to catch fire and make a run. That serious and credible candidate is not Donald Trump."

Trump's profanity-laced tirade at a rally in Las Vegas on April 28 didn't exactly help the billionaire pivot toward a more presidential image. But not all Republicans are willing to rule out that Trump could try to become a bona fide contender, with a full campaign apparatus and serious policy positions. He just hasn't taken that step yet. In an interview with the Las Vegas Review-Journal published May 1, Trump was asked if he had a pollster. His reply: "I don't need pollsters. You know what my poll is? It's my brain. My poll is my brain."

For anyone to win the GOP nomination, let alone the White House, it will take a focused machine with a solid tactical plan, notes Ford O'Connell, chairman of the conservative Civic Forum PAC.

"Not every campaign has the luxury of having a Karl Rove or David Axelrod on staff, but it will certainly take more horsepower than Trump is currently surrounded by," Mr. O'Connell says. "Additionally, Donald Trump has to understand that to win the GOP nomination, he has to be willing to take direction from his campaign team or he will continue to have serious gaffes and unforced errors on the campaign trail, like he recently did in Nevada."

But, O’Connell adds, “thus far, I am not seeing any evidence that Trump is taking the necessary steps to be a viable contender.”

Even if he gets serious about staffing and cleans up his act, Trump may have too much baggage to catch on in a big way. He has a history of donating to Democratic politicians. He is on his third marriage. And he used to espouse quite a different policy line, including favoring tax increases, single-payer health care, and abortion rights.

Trump's financial history, which has had its ups and downs, would also be fertile ground for media investigation. With a net worth in the billions, Trump could self-finance a campaign, but he would still need to raise money to show voter buy-in.

Some voters cite his business success and willingness to go after Obama as reasons to support him, but some Republicans aren't sure that's enough to mount a credible campaign.

"He's a successful businessman, but there's a big difference between dealing with real estate brokers in New York and dealing with [Russian Prime Minister Vladimir] Putin," says GOP pollster David Winston. "And the idea of simply saying we're going to take Libya's oil just doesn't work. While initially that may sound entertaining, people understand it takes more than that to deal in international affairs."

Obama also had to address the inexperience question when he ran four years ago. But now he is the incumbent, and, on the international stage, has garnered the most compelling experience of all: overseeing the operation that got Osama bin Laden. The birther issue suddenly looks especially small.

In the end, general-election voters suggest that Trump is just plain unelectable. A majority of Americans – 58 percent – say they "would never vote for" Trump, according to the Quinnipiac poll. The only other potential candidate who scored a majority in the "never vote for" column was Ms. Palin, also at 58 percent.