A senior Liberal has endorsed Sussan Ley as party leader while reinforcing immigration concerns that prompted rogue MP Andrew Hastie to abandon the front bench.

As one of the party's few remaining representatives in an outer-urban seat, western Sydney MP Melissa McIntosh said she understood why Mr Hastie made the decision to quit shadow cabinet to speak more freely about immigration.

The now-former home affairs spokesman announced his resignation late on Friday, saying he felt he wouldn't be able to uphold cabinet solidarity.

"I can feel that for him because I come from an outer-metro seat where high immigration is putting pressure on infrastructure," Ms McIntosh, the opposition's communication spokeswoman, told Sky News on Sunday.

"Infrastructure costs are out of control. Our hospital

See Full Page