Rep. Henry Cuellar of Texas says he's a loyal Democrat, but he believes President Obama is starting to "look detached" by not visiting the border during his trip to Texas this week.

Cuellar said he was dumbfounded when he saw pictures of the president making a casual evening stop in Colorado as he made his way to Texas.

"Look, he's going to be in Austin, 242 miles away from the border. He's going to be in Dallas, 500 miles away from the border," Cuellar told ABC News. "We saw some of the photographs where he was in Colorado, drinking a beer, playing pool. I mean the optics are just horrible."

As the crisis at the border escalates, with no quick solution in sight to stem the tide of unaccompanied minors arriving illegally from Central America, several Texas Democrats are voicing rare criticism of a president in their own party. Cueller has been unusually blunt and outspoken at the president's decision not to visit the border, which he said resulted in a phone call from the White House.

"I'm a Democrat, but I will always put party behind what I think is in the best interests of the country," Cuellar said in an interview on Capitol Hill. "Again, I'm more concerned about the people I represent in Texas than somebody else, with all due respect."

Cuellar, who has served in Congress since 2005, represents a deep Southern Texas district that stretches to the U.S. border. He said the president would be better equipped to tackle the immigration crisis if he witnessed the conditions first-hand.

"If you go down to the border, he has to see the kids that I've seen, young girls, young boys, you know, that have come through very difficult situations. It is a humanitarian crisis, and he can either do two things," Cuellar said. "One, as a leader, he can be defiant and say I'm going to roll up my sleeves and see the humanitarian crisis. Or he can look detached, appear detached and say I'm doing everything long distance."

The president is set to meet with Gov. Rick Perry of Texas during his overnight trip to Dallas and Austin, but Cuellar said that isn't enough.

"A leader will be judged by how he handles a crisis. He can roll up his sleeves or go down to the border or he can look detached and say I got everything under control," Cuellar said. "But when you still have 48,000 people coming across a month on the Texas border, I think that's a humanitarian crisis that the president should give a little personal attention to."

Rep. Joaquin Castro, D-Texas, took a softer tone, but said he also wished the president would visit the border.

"He should go down and this week is not his last opportunity to do that," Castro told ABC News. "This is a situation that we know is going to be going on for a while and I hope that eventually he'll make it down there."