Getting your Trinity Audio player ready...

President Bush is planning to issue a stern warning Wednesday that the United States will not accept a political transition in Cuba in which power changes from one Castro brother to another, rather than to the Cuban people.

As described by an official in a background briefing to reporters Tuesday evening, Bush’s remarks will amount to the most detailed response — mainly an unbending one — to the political changes that began in Cuba a year ago, when Fidel Castro fell ill and handed power to his brother Raul.

The speech, scheduled to be given at the State Department before invited Cuban dissidents, will be a call for Cubans to continue to resist. He is expected to say to the Cuban military and police, “There is a place for you in a new Cuba.”

Some of the sharpest parts of the speech, however, will be aimed directly at Raul Castro. Bush is expected to make clear that the United States will oppose an old system controlled by new faces. The senior administration official said the U.S. would uphold its tough economic policies against the island.

However, he held out the possibility of incentives for change, including expanding cultural and information exchanges. The administration official gave no reason for the timing of Bush’s speech. However, he did say another important constituency is the international community, particularly those countries whose trade with Cuba undermined the impact of the U.S. embargo. In recent months, Raul Castro has made an open play for more business, suggesting his government is prepared to carry out reforms.