Republican In Name Only

Republican In Name Only is a pejorative term used by conservative members of the Republican Party of the United States to describe Republicans whose political views or actions they consider insufficiently conservative. The acronym RINO emerged in the 1990s.

In 1912, former President Theodore Roosevelt, then-President William Howard Taft, and Senator Robert M. La Follette Sr. fought for ideological control of the Republican Party and each denounced the other two as "not really Republican". The phrase Republican in name only emerged as a popular political pejorative in the 1920s, 1950s and 1980s.

The earliest known print appearance of the term RINO was in the Manchester, New Hampshire newspaper then called The Union Leader.

Bill Clinton would have been proud of what was happening on the third-floor Senate corner at the State House this week.... The Republicans were moving out and the Democrats and "RINOs" (Republicans In Name Only) were moving in.

Buttons featuring the red slash through an image of a rhinoceros were spotted in the New Hampshire State House as early as 1992. In 1993, former Marine and future California Republican Assembly President Celeste Greig distributed buttons featuring a red slash over the word RINO to express opposition to Los Angeles mayor Richard Riordan. The term came into widespread usage during subsequent election cycles.

That little sobriquet is so baseless and so outrageous... [it was] ginned up by people who don't believe you can be a Republican unless you're hard right on social issues.

During Republican primary campaign season, some conservative organizations target RINO Republicans who fail to adopt their stances. National Federation of Republican Assemblies started the "RINO Hunters' Club", whom they believe to be too moderate on such issues as taxes, gun rights, and abortion. The fiscally conservative 501(c)4 organization Club for Growth invented the "RINO Watch" list to monitor "Republican office holders around the nation who have advanced egregious anti-growth, anti-freedom or anti-free market policies"; other conservative groups published similar lists.

...
Wikipedia