McALLEN - U.S. Sen. Hillary Clinton is expected to endorse Democratic Senate hopeful Rick Noriega on Thursday during a fundraising trip to the Valley.

The former first lady will appear with the candidate at an afternoon press conference at the McAllen-Miller International Airport, Noriega's campaign said in a statement.

Clinton's visit to the Valley comes six months after she won the Democratic presidential primary race in the region with more than 70 percent of the vote. She eventually conceded the race to her rival and current party nominee, Barack Obama.

She is expected to attend a fundraising dinner for her political action committee later Thursday evening hosted by real estate developer and long-time Clinton ally, Alonzo Cantu.

Noriega, a state representative from the Houston area and 27-year military veteran, is currently embroiled in a bid to oust U.S. Sen. John Cornyn, R-Texas, in November elections.

He is scheduled to speak at a Young Democrats rally Thursday afternoon on the campus of the University of Texas-Pan American and Friday morning at a breakfast meeting of the McAllen Hispanic Chamber of Commerce.

But quick to challenge their opponent's Valley visit, the Cornyn campaign shot back Thursday morning with a statement pointing out a number of endorsements the Republican senator has received in one of Texas' few Democratic strongholds.

Zapata County Sheriff Sigifredo Gonzalez, Elsa Mayor Senovio Castillo, and police chiefs in Mission, Weslaco, Pharr, Palmview and Alton have all pledged their support to Cornyn, according to the his campaign.