“Reform Judaism is the Democratic Party platform with religious holidays thrown in” is a jocular one-line saying that has been popular with Republicans. Richard Brookhiser, a senior editor at National Review, has been credited with coining the remark. “And Jewish renewal turns out to be little more than, well, as Brookhiser put it, the Democratic Party with holidays” was published in American Spectator in December 1994.
 
         
Wikipedia: Richard Brookhiser
Richard Brookhiser (born February 23, 1955) is an American journalist, biographer and historian. He is a senior editor at National Review. He is most widely known for a series of biographies of America’s founders, including Alexander Hamilton, Gouverneur Morris, and George Washington.
 
Google Books
The American Spectator
Volume 27
December 1994
Pg. 79:
And Jewish renewal turns out to be little more than, well, as Brookhiser put it, the Democratic Party with holidays.
       
First Things 
GETTING THE SIDES STRAIGHT
THE PUBLIC SQUARE
by Richard John Neuhaus
February 1995
(...)
And Jewish renewal turns out to be little more than, well, as [Richard] Brookhiser put it, the Democratic Party with holidays.
 
Google Books
Jewish Power:
Inside the American Jewish Establishment
By J. J. Goldberg
Reading, MA: Basic Books
1996
Pg. 25:
Richard Brookhiser, a conservative essayist, once suggested that the only difference between the Democratic Party and Reform Judaism was the holidays.
 
Fall 1998, Judaism (New York, NY), “Liberal politics and American Jewish identity” by Edward Shapiro, pg. 429:
Thus Richard Brookhiser, the conservative writer and senior editor of William F. Buckley’s National Review, quipped that the only difference between Reform Judaism and the Democratic Party was their respective holidays.
 
24 September 1998, Jewish Advocate (Boston, MA), “Jewish group’s spin for survival of president spirals out of control” by Jonathan S. Tobin, pg. A13:
Every election year we joke about Jews who define Judaism as the Democratic Party platform with holidays thrown in, but there are a significant number of Jews who feel that way.
 
4 June 1999, The Desert Sun (Palm Springs, CA), :Liberal Jews are swinging back to conservative standards” by Mona Charen,  pg. B5, col. 1:
Pundit and historian Richard Brookhiser once quipped that Reform Judaism struck him as “the Democratic Party with holidays.” A recent survey conducted on behalf of the American Jewish Committee would seem to confirm that analysis.
   
New York (NY) Post
A TRIBE DIVIDED
By Zev Chafets March 15, 2007 | 9:00am
(...)
This, in itself, wasn’t shocking. Reform Judaism is, in the memorable phrase of author Richard Brookhiser, “the Democratic Party with holidays.”
         
Google Books
Why Are Jews Liberals?
By Norman Podhoretz
New York, NY: Doubleday
2009
Pg. 287:
Someone once unkindly described the services in a Reform temple as “the Democratic Party at prayer,” and Reform Judaism in general as “the Democratic Party platform with holidays thrown in.
 
Twitter
cup ‘o joe ☕️‏
@JoeNYLaw
Definition of so-called Reform Judaism: The Democratic Party platform with a few holidays thrown in.
7:59 PM - 14 Mar 2010
 
Los Angeles (CA) Times
Op-Ed Jewish Americans don’t vote with Israel in mind, they vote as liberals
Jonathan Bronitsky
OCTOBER 28, 2016, 4:00 AM
(...)
Reform Judaism has been called “the Democratic party platform with holidays thrown in,” and the services in a Reform temple have been described as “the Democratic Party at prayer.”
 
Twitter
Gidon Ariel‏
@gidonariel
Replying to @haivri
what’s the surprise? You know what they say: Reform Judaism is the Democratic Party with holidays thrown in
11:04 AM - 10 Nov 2016
 
Twitter
Mark Jacobs‏
@mr_markjacobs
Replying to @RQA
Old Jokes: Reform Temple: The Democratic Party at prayer. Reform Judaism: The Democratic Party platform with holidays thrown in.
5:39 PM - 4 May 2017
 
Haaretz
Opinion Leave the Jews Out of the Trump Debate
Why mix up the legitimate debate around the administration’s political circus with hyperbole about the ‘danger’ the president poses to American Jews?
Jonathan S. Tobin Jun 19, 2017 10:27 AM
(...)
The liberal social justice agenda is integral to his religious worldview. But he should be cautious about lending credence to the old joke about Reform Judaism being the Democratic Party platform with religious holidays thrown in.