Sanders has surged in polls in New Hampshire.
"He stopped serving as an umpire," the 2016 GOP candidate said.
Bundy made headlines last year and became the face of a land rights standoff in Nevada.
Bush's release pressures Hillary Clinton to release her latest financial figures.
Christie, Kasich and Bush are among the candidates putting their chips in New Hampshire.
He has hit the Supreme Court with repeated rhetorical barbs over same-sex marriage.
The 2016 contender on Monday made his first campaign stop in South Carolina since the shooting.
O'Malley's call comes days after the Supreme Court legalized same-sex marriage.
Trump says decision to cut ties is "weak" and "foolish."
The network is severing its relationship over recent comments about immigrants.