WASHINGTON — Allstate Corp. says it has decided not to participate in the federal Troubled Asset Relief Program.

Allstate, Northbrook, Ill., already has enough cash and capital on hand, the company says.

The Treasury Department has given Allstate and five other insurers preliminary approval to participate in the Capital Purchase Program, a TARP subprogram.

One of the insurers, Ameriprise Financial Inc., Minneapolis, immediately announced that it would not participate in the CPP.

Prudential Financial Inc., Newark, N.J., and Principal Financial Group Inc., Des Moines, Iowa, said they are still deciding whether to participate.

The insurers approved for CPP participation applied for the program in late 2008, when the credit markets were frozen. Since then, the credit markets have thawed.

Congress and Treasury officials have responded to criticism of TARP by moving to put limits on participating institutions’ dividend payments and executive compensation programs.

Allstate disclosed its decision to decline TARP aid along with an announcement that the company will pay a quarterly dividend of 20 cents per share.

Allstate had more than $12 billion in equity and more than $23 billion in cash and other highly liquid assets at the end of the first quarter, according to Allstate Chairman Thomas Wilson.

“These positions reflect proactive capital management steps taken over the past year, including suspending [the] share repurchase program, augmenting investment risk mitigation programs and reducing operating costs,” the company says.

Since the end of the first quarter, Allstate has completed a $1 billion debt offering, and the company’s securities portfolio value has increased by about $1.5 billion, the company says.

“Maintaining our financial strength is a top priority in 2009, and we will continue to take proactive steps to manage our capital position as markets develop and the economy improves,” Wilson says.