Peter Black CBE has said that a "large influx of English voters" has made it "much harder" for the Welsh Liberal Democrats to win in rural parts of the country.
The former Welsh Liberal Democrat MS said that the areas in which the party has traditionally won seats have "changed beyond recognition".
Black said: "Rural Wales is no longer populated by traditional liberals", but rather "a large influx of English voters".
Black also said that although these seats have become more difficult for the party to win, they continue to focus their resources in those areas "at the expense of the rest of Wales."