Byron Davies joined 308 Conservative colleagues in voting to cut the Employment Support Allowance paid to disabled people. Not a single MP from any other party voted for the cuts.
Rebecca Evans worked for a major disability charity before being elected as a regional AM, and has since Chaired the Assembly's Cross Party Group on Disability.
Rebecca Evans said: "Byron's claim to care about the needs of the people of Gower is simply not matched by his voting record in Westminster.
"The Tories' cuts are hitting the most vulnerable hardest. A third of disabled people already live in poverty, and this huge cut to disability benefits that he has supported will push still more into poverty. That is an absolute travesty.
"Under the Tories the UK has achieved the dubious accolade of becoming the first country ever to face a high-level inquiry by a United Nations Committee into charges of “grave or systemic violations” of disabled people’s rights. That is both shocking and shameful.
"Voting to cut disability benefits is vindictive and spiteful. It is also a false economy, as pushing people into poverty has high-cost implications for pressures on health and social care services. The Conservatives would be better off creating employment and training opportunities for disabled people."
The cut will mean that the support received by disabled people will be slashed from £103 to £73 per week.