This Nixon-era memo shows how Republicans have been practicing white identity politics for decades

Conservatives often criticize the Democratic Party for playing "identity politics," which in their view involves appealing to voters based on their race, religion or ethnicity instead of appealing to a common identity as American citizens.

However, a 1971 memo written by one-time Nixon speechwriter Pat Buchanan demonstrates how Republicans have been practicing identity politics for decades.

In the memo, Buchanan makes an argument that Nixon's reelection campaign should all but write off black and Jewish voters and instead focus on what he describes as "minority" communities within white America -- that is, working-class Catholic voters of Irish, Italian, and Polish descent who had traditionally voted for Democrats.

"Nowhere does one see proper recognition of the hard political fact that while there are six million Jews in this country, 22,000,000 blacks,­

there are some 46,000,000 Catholic," Buchanan wrote. "Not only are the Catholic by far the hugest bloc of available Democratic votes to win for us -- they are... the easiest to convert."

Buchanan went on to recommend that the Nixon administration appeal to these voters in part by making high-profile appointments of officials with Catholic backgrounds to key administration positions -- even though conservatives have regularly called appointments based at least partly on ethnicity a kind of quota that potentially penalizes more qualified candidates.

"My recommendation is now and has been that the Administration -- in placing minority members in visible jobs -- stop concentrating on the "media's minorities" (Blacks, Mexican Americans, Spanish-speaking) which are tough to crack, almost solid Democratic -- and begin focusing on the ethnic minorities (Irish, Italians, Poles, Slovaks, etc.), the big minorities where the president's name is not a dirty word."

History would show that Buchanan's strategy proved successful for Nixon.

Polling data from Gallup found that Democrats' hold on the Catholic vote peaked in 1960 with the election of President John Kennedy, who won an estimated 78% of all Catholic votes.

That number would shrink in subsequent elections, however, and Nixon would actually win the Catholic vote in the 1972 election, marking the first time a Republican had won a majority of Catholic voters since Gallup began its polling.

Catholic voters similarly were drawn to President Ronald Reagan in the 1980s, although since they have overall gone back to leaning toward Democrats -- though not in the same overwhelming numbers the party enjoyed in the 1960s.

Read Buchanan's full memo here.