The post said, "And we thank our fellow citizens who are supporting them".
In the photo, Bush can be seen carrying boxes of pizza to his secret service detail.
The shutdown has entered a fifth week and is the longest in USA history.
"It's time for leaders on both sides to put politics aside, come together and end this shutdown", the post said.
Secret Service agents, charged with protecting current and former presidents and their families, have remained on duty throughout the shutdown - but the stress of working without pay has hit many of them hard.
Siguen triunfos de Halep y hermanas Williams
La española Garbiñe Muguruza, 18va preclasificada, también se mantiene con vida en el torneo, como Elise Mertens (12da) y Anastasija Sevastova (13ra).
Consequently, a government shutdown has been in effect since funding expired on December 21.
Bush also urged politicians to come together to put an end to the shutdown. US President Donald Trump is demanding United States dollars 5.7 billion to build more than 200 miles of his proposed southwest border wall, and has refused to sign spending bills reopening government lacking that money.
"Congress has already passed a bill that guarantees all federal employees back pay once the shutdown is over, but that does little to help them while it drags into its fourth week".
In the week prior to the Christmas recess, Trump initially signaled that he would sign a stopgap measure passed unanimously in the Senate that funded the government until February 8, even though it did not include border wall funds.
The shutdown stems from a disagreement over funding for a barrier at the nation's southern border. As the shutdown - which is the longest in modern history - approaches the month-long benchmark, it's unclear how this will end.