Washington (CNN) The Transportation Security Administration is making a plea for 250 people to bolster its workforce of backup officers, the latest sign the agency is straining under the pressure of the shutdown, according to an internal email sent Monday morning from a TSA executive and obtained exclusively by CNN.

The email, sent to TSA officials in more than 10 states with more than 100 airports, asks for employees to move from their home airports to those airports struggling with low staffing, an indication the agency is bracing for even more callouts.

The email is the latest example of increasing anxiety within TSA about the rising number of callouts as employees prepare to miss a second paycheck this week. Ten percent of TSA's workforce had unexcused absences on Sunday, the agency said.

This is the second such request for more backup screeners to help fill staffing gaps, according to the email and a TSA official familiar with its contents.

All members of the agency's National Deployment team, a rapid response team comprising of TSA officers can be sent to airports across the country to help fill the staffing gaps, have already been dispatched, according to the email. The team has been used to patch up gaps at airports in Atlanta, New York, Chicago and elsewhere as the partial government shutdown extends into its fifth week.

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