BP’s (NYSE: BP) Macondo play in the Gulf of Mexico has leaked oil for more than a month, and public frustration is growing.

From a political perspective, this presents a problem for the Obama administration. At first the public supported the President’s reaction to the spill, but polls indicate that opinions are changing, and Obama’s approval ratings have declined.

The comparison between President Obama’s handling of the BP spill and President Bush’s handling of the Katrina disaster back in 2005 has been particularly damaging. The hurricane’s devastating blow to New Orleans proved a political nightmare for the former President. The reality is that there’s not much either President could have done differently that would have had a meaningful impact. But public perception is reality in politics.

And few men are more dangerous than a wounded politician. The Obama administration has taken a decidedly more aggressive tack toward the energy industry in the deepwater Gulf of Mexico, stepping up rhetoric and extending the drilling moratorium in the Gulf.

I devoted the entire May 5, 2010, issue of The Energy Strategy to the Macondo disaster and an analysis of the stocks most likely to be affected. As I noted then, I saw the potential for further extensions to the moratorium on granting new drilling permits and suspected that the government might cancel new Gulf of Mexico lease sales.

On May 27 President Obama did just that, extending the moratorium on new offshore well permits by a further six months and canceling two planned lease sales. But many analysts were surprised when the Administration announced that wells currently being drilled in water deeper than 500 feet deep will be halted as soon as it is safe for producers to stop operations. This mandate covers 33 wells currently being drilled, and, by extension, 33 deepwater rigs drilling those wells.

Because BP’s so-called “top-kill” operation failed to stench the oil flow, I see little chance that the anti-deepwater rhetoric will calm down anytime soon. The moratorium could be extended beyond six months–a risk that becomes more likely the longer the well remains out of control.

The sector that’s most likely to be negatively impacted by the moratorium is the offshore contract drillers. Most drilling contracts contain force majeure clauses that are triggered after drilling is interrupted for a certain period of time. Once triggered, the day-rates drop to a slightly reduced rate for a period, after which the producer has the right to cancel the contract.

These clauses aren’t identical, but a good rule of thumb is that if the contracts were signed during a period of high rig demand, or for highly capable ultra-deepwater rigs, force majeure provisions are likely to be more favorable for the contract driller.

The moratorium won’t affect shallow-water jackup drillers in the Gulf of Mexico; jackups typically operate in shallower waters. On the one hand, jackup contractors might face more safety inspections and higher insurance premiums. But a lack of drilling opportunities in the deep is likely to accelerate activity in shallower water.

The worst affected contract drillers are those with older rigs and heavy exposure to the Gulf of Mexico. Topping the list is Diamond Offshore (NYSE: DO), a stock I rate a “Sell” in my How They Rate coverage universe. As I noted in the May 26, 2010, Flash Alert, Buying the Dip, I recommended standing aside from Noble Corp until we got more clarity on the moratorium. I’m downgrading Noble Corp to a Hold in How They Rate.

Transocean (NYSE: RIG) hasn’t appeared in the model Portfolios since 2006. Although I expect the company’s liability from Macondo will be minimal, the firm is exposed to the moratorium and has a fleet of older rigs that may require significant upgrades under new US regulations likely in the wake of the moratorium. I’m downgrading Transocean to a Hold in How They Rate.

Seadrill (NYSE: SDRL) remains my favorite offshore contract drilling firm. As I noted in previous issues, Seadrill has a new fleet and only a little over 5 percent of revenues come from the Gulf of Mexico.

Of the company’s 14 deepwater drillships and semi-submersibles, only one operates in the US Gulf of Mexico: the West Sirius a fifth-generation rig capable of drilling in waters up to 10,000 feet deep. Because this rig went into service in July 2008–the height of the boom–I suspect it’s covered by a contract that’s generous to Seadrill.

Better still, Seadrill reported solid earnings results late last week and hiked its quarterly dividend to $0.60 from $0.55–the stock now yields an impressive 11.6 percent. Seadrill rates a buy under 29, with a stop at 16.25.

Investors should note that not all financial websites reflect the correct dividend for Seadrill. Because the stock has only paid two consecutive quarterly dividends to date, many websites base the company’s yield calculation on that historic payout. Seadrill now pays dividends quarterly, and those payouts look likely to rise; historic yield calculations massively understate the company’s income potential.

I also see the moratorium as a positive for onshore-focused contract drillers such as Gushers recommendation Nabors Industries (NYSE: NBR). A decline in offshore drilling activity may prompt more activity onshore and shifts attention away from the any regulation of hydraulic fracturing.

In addition, investors looking for exposure to energy will now be rotating out of the troubled and formerly popular offshore names like Diamond Offshore and Transocean and into stocks like Nabors.

Finally, Royal Dutch Shell (NYSE: RDS.A) became the latest major international oil company to make a major investment in an unconventional US natural gas play last week. Buy Nabors Industries under 28.

Shares of pure-play services firms also took a hit when the drilling ban was announced. The moratorium is expected to weigh on services outfits, but operations in the Gulf of Mexico account for only 5 to 10 percent of our favorite name’s revenues. Weatherford International (NYSE: WFT) comes in at the lower end of that range, while Baker Hughes (NYSE: BHI) is toward the upper limit. Accordingly, Weatherford outperformed the group last Friday, whereas Baker Hughes underperformed.

The most bearish estimates I have seen forecast that the moratorium will reduce earnings 25 to 30 percent over the next quarter or two. But that activity will simply shift elsewhere, and a drop of that magnitude–hardly the most likely scenario–is already more than priced into these stocks.

Regard any weakness in Schlumberger (NYSE: SLB), Weatherford International (NYSE: WFT) and Baker Hughes (NYSE: BHI) as a buying opportunity.