Rep. Jeff Flake, who is running for U.S. Senate.

The campaign manager for the presumptive Democratic nominee for U.S. Senate, Richard Carmona, is predicting a “long, hot and miserable summer” for the front-runner, U.S. Rep. Jeff Flake.

In a memo titled, “State of the Race,” Alexis Tameron says the the Republican primary between Flake and Wil Cardon is becoming more costly everyday causing "damage to the brand Congressman Flake has spent six terms building.”

“It is becoming clear to local prognosticators that whoever emerges from this primary battle will have difficulty marshaling the resources, political strength and centrist credibility needed to win the Independent and moderate voters needed to win this race,” predicted Tameron, Carmona’s campaign manager.

She says Carmona’s internal polling shows he leads Flake 49-44 percent. Republican-leaning Magellan Strategies, however, still shows Flake leading 44-40 percent lead on Carmona. They say Cardon has a 41-40 lead on Carmona.

Tameron highlights the importance of independent voters.

Voter registration figures show that Carmona must capture independent voters if he has any chance of becoming Arizona’s first new U.S. Senator in 18 years.

There are 181,000 more registered Republican voters than Democrats in Arizona, and independents also outnumber Democrats by 84,000.

In the conclusion of the memo, Tameron offers her prediction for the summer months ahead as Flake tries to fend off Cardon, a wealthy Mesa businessman who has already put $4.2 million of his own money into the race.

“It’s going to be a long, hot and miserable summer for Congressman Flake,” Tameron wrote.

Flake posted a response to his Twitter account this afternoon:

“@carmonaforaz predicts hot miserable summer 4 me. He's right. I've got races 2 win. No cool, cushy confines of Canyon Ranch for me,” Flake wrote, in reference to Carmona’s position as president of the board of directors for the Canyon Ranch health resort in northeast Tucson.

Flake’s spokesman, Andrew Wilder, said in an email that people should take the memo as seriously as “summertime snow forecasts in Tucson.

Stay tuned to the Pueblo Politics blog throughout 2012 for news, updates and information about Arizona politics. You can follow Arizona Daily Star reporter Brady McCombs by clicking on his name.