Former Vermont Gov. Howard Dean’s (D) presidential campaign continued to pick up momentum Monday, securing the backing of Rep. Rául Grijalva (D-Ariz.) in a key early primary state.

Dean was set to receive Grijalva’s endorsement at a 12:30 p.m. event at Presidio Park in downtown Tucson.

“I believe Governor Dean is the only one that can unseat President Bush and take this country into a new era,” said Grijalva. “His leadership will provide Arizona and the rest of our nation with a sense of values that will benefit all Americans.”

Grijalva’s endorsement brings to six the number of House and Senate Members endorsing the Dean campaign. Aside from home state Sens. Patrick Leahy and Jim Jeffords , Reps. Zoe Lofgren (Calif.), Neil Abercombie (Hawaii) and Frank Pallone (N.J.) are supporting Dean.

Arguably, Grijalva’s support is the most important of that group. One of two Democrats in the state’s Congressional delegation (Rep. Ed Pastor has endorsed Missouri Rep. Richard Gephardt’s presidential bid), Grijalva is wildly popular in the Hispanic community. Hispanics make up roughly one-quarter of the state’s population, and are a significantly larger chunk of the Democratic primary electorate. Dean called Grijalva an “inspiration to Latinos and all Americans.”

The Grand Canyon State primary is set for Feb. 3, just after the Jan. 19 Iowa caucuses and Jan. 27 New Hampshire primary. South Carolina, Delaware, Missouri, New Mexico and Oklahoma will also hold primaries or caucuses on the first Tuesday in February.

In other presidential endorsement news, Rep. Leonard Boswell (D-Iowa) denied a report in Monday’s Boston Globe that he has endorsed Sen. John Kerry (Mass.).

Apparently, Boswell gave a rousing speech introducing Kerry at an event in Iowa last week but remains neutral in the presidential race. His support is seen as crucial as he is the lone Democrat in the state’s House delegation. Sen. Tom Harkin (D-Iowa) is holding a series of forums around the state for the presidential candidates and is expected to endorse when the process concludes in late September.