Bob Dole hospitalized at Walter Reed

Former Republican presidential candidate and Senate majority leader Bob Dole has been hospitalized since last week, Fox News has learned.

Dole, who turned 94 in July, was admitted to the hospital last Wednesday at Walter Reed National Military Medical Center in Bethesda, Md., after having low blood pressure.

"After a routine check-up, he experienced a brief bout of low blood pressure, which they are correcting with medication," Dole's communications director, Marion Watkins, told Fox News on Friday.

Watkins told Fox News that doctors have kept Dole for "observation" until they can determine the medication is effective.

“Thank you all for your prayers and well wishes. I hope to be home sipping a cosmo in a few days,” Dole tweeted early Friday, in response to a tweet from his wife’s “Dole Foundation” account.

“Sorry to miss #InvictusGames2017. I’m with my husband, @SenatorDole, at the hospital. Please pray for his speedy recovery,” his wife, former Sen. Elizabeth Dole, R-N.C., had tweeted Friday.

Watkins told Fox News that the senator’s hospital admission was out of “an abundance of caution,” and doctors are hoping to release him within a matter of days.

Dole’s career in politics is extensive – he was the longest-serving Republican leader in the Senate; was the Republican presidential nominee in the 1996 election; and ran as the vice presidential nominee in the 1976 election. In 2007, President George W. Bush appointed Dole as co-chair of the commission to investigate problems at Walter Reed Army Medical Center.

Dole currently serves as special counsel to law firm Alston & Bird in Washington, D.C.

"He is in good spirits," Watkins told Fox News. "He appreciates everyone's well wishes."