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WESLACO, Texas (AP) — Gov. Greg Abbott remains noncommittal on a timeline for pulling the National Guard off the Texas-Mexico border after hundreds of police officers applied for jobs to effectively replace those troops.

Abbott toured the border Friday with Wisconsin Gov. Scott Walker, a likely Republican presidential contender. But Walker was out of sight to reporters after arriving in Texas hounded by uncomfortable new questions about his stance on immigration.

Abbott has not endorsed anyone for 2016.

The crowded Republican field already includes Texas Sen. Ted Cruz , who is Abbott’s one-time protégé. Former Gov. Rick Perry is gearing up for his own expected announcement.

Abbott says the National Guard can’t leave until state troopers replace them. More than 700 law enforcement officers in Texas recently applied to fill fast-tracked trooper positions.

(© Copyright 2015 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)