John McCain’s presidential campaign, playing an aggressive version of the expectations game, circulated a campaign memo predicting Barack Obama will get a nearly 15-point bump in the opinion polls as a result of next week’s Democratic Convention.

The memo comes as Obama kept the country — and the increasingly frenzied media — in the dark about who he had picked as his vice presidential candidate.

The McCain campaign already is looking at ways to steal some of Obama’s spotlight in the coming week, with a plan for instant responses to speeches by Obama and his supporters.

Even so, McCain aides are predicting that Obama’s short-term success could rival that of Bill Clinton’s, who got a 16-point bump in the polls after he was named the Democrat’s nominee at the 1992 convention in New York.

“Barack Obama is more similarly situated to Bill Clinton in 1992 than any other candidate in recent history,” Sarah Simmons, a director of strategy for the McCain campaign, wrote in the Friday memo. “Bill Clinton was a new candidate on the national scene; he was running in a ‘change’ oriented election cycle and the economy was voters’ top issue — a dynamic he was able to capitalize on.”

The McCain campaign also expects Obama, who is leading McCain 42 percent to 39 percent in a FOX News poll released this week, to get a temporary 5-point bump from announcing who he has chosen as his running mate.

Obama is scheduled to appear with his vice president pick tomorrow in Springfield, Illinois. The convention starts Monday in Denver.

The McCain campaign expects Obama to deliver a “great speech” Thursday, after which the press “will sing his praises.”

“Obama will correct his underperformance with Hillary Clinton’s primary votes and emerge with a much more cohesive base,” Simmons continued. “This convention gives Obama a platform to unite his base.

“This coverage will be impenetrable and will undoubtedly impact the polls.”

Campaigns often try to set expectations high for their opponents so that even a significant bump in the polls might seem a failure if it falls lower than predicted.