All Pew Research Center surveys about U.S. politics and policy include questions about partisan affiliation. In 2014 a total of 25,010 respondents were asked the following:

In politics TODAY, do you consider yourself a Republican, Democrat, or independent?
(IF INDEPENDENT, OTHER, DON’T KNOW): As of today do you lean more to the Republican Party or more to the Democratic Party?

Detailed demographic breakdowns of party identification are presented here, or can be downloaded (CSV or PDF).
Report: A Deep Dive Into Party Affiliation

TotalWhite, Non-HispanicBlack, Non-HispanicHispanicAsian, Non-Hispanic

Among Non-Hispanic Whites

Rep % Dem % Ind % (VOL.)
Other/DK %		 Rep/Lean
Rep %		 Dem/Lean
Dem %		 No
leaning %		 Unweighted N
ALL WHITE NON-HISPANIC
30 25 40 5 49 40 11 17,823
GENDER
White NH Men 31 20 45 4 53 36 11 9,072
White NH Women 29 30 35 5 45 44 11 8,751
GENERATION
White NH Millennial (ages 18-33 in 2014) 25 22 49 4 45 43 13 2,936
White NH Generation X (34-49) 30 25 40 5 50 39 12 3,431
White NH Baby-Boomer (50-68) 30 27 38 5 49 40 11 7,200
White NH Silent (69-86) 37 27 31 5 53 37 9 3,702
DETAILED GENERATION
White NH Younger Millennial (18-25) 24 21 51 4 46 43 11 1,430
White NH Older Millennial (26-33) 25 22 48 5 44 42 14 1,506
White NH Younger Gen Xer (34-41) 29 24 42 5 48 39 12 1,455
White NH Older Gen Xer (42-49) 31 25 39 5 50 39 11 1,976
White NH Younger Boomer (50-58) 31 26 38 6 50 39 11 3,232
White NH Older Boomer (59-68) 30 29 38 4 48 42 10 3,968
White NH Younger Silent (69-78) 36 27 32 5 53 38 9 2,631
White NH Older Silent (79-86) 39 28 29 4 54 37 9 1,071
EDUCATION
White NH College graduate+ 28 30 38 3 46 47 7 8,009
White NH Post graduate degree 23 37 37 3 40 54 6 3,158
White NH College graduate 31 26 39 4 50 43 7 4,851
White NH Some college or less 31 23 41 5 50 37 13 9,763
White NH Some college 32 22 42 5 52 37 11 4,930
White NH High school or less 30 24 40 6 48 37 15 4,833
FAMILY INCOME
White NH $75,000+ 34 26 38 3 53 40 7 6,073
White NH $30,000-$74,999 30 25 41 4 50 40 10 5,723
White NH <$30,000 24 27 43 6 41 44 15 4,092
DETAILED FAMILY INCOME
White NH $150,000+ 34 26 38 3 52 41 7 1,763
White NH $100,000 to $149,999 34 26 37 3 54 41 6 2,089
White NH $75,000 to $99,999 34 25 38 3 54 39 8 2,221
White NH $50,000 to $74,999 33 24 39 4 53 38 9 2,687
White NH $40,000 to $49,999 30 26 41 3 49 41 10 1,485
White NH $30,000 to $39,999 27 26 44 3 46 42 12 1,551
White NH <$30,000 24 27 43 6 41 44 15 4,092
EMPLOYED
White NH Yes 29 24 41 5 47 41 12 1,388
White NH Full-time 30 23 41 5 48 39 13 1,035
White NH Part-time 27 26 42 6 44 46 10 353
White NH No 29 26 37 8 45 40 15 920
MARITAL STATUS
White NH Married 34 22 40 5 55 34 10 5,315
White NH Unmarried 23 27 45 5 40 46 14 4,041
DETAILED MARITAL STATUS
White NH Married 34 22 40 5 55 34 10 5,315
White NH Living with a partner 16 26 54 4 36 50 14 491
White NH Divorced/Separated 23 30 41 6 42 44 14 1,207
White NH Widowed 31 32 32 5 46 42 11 997
White NH Never married 22 25 49 5 39 47 14 1,346
PARENT OR GUARDIAN
White NH Yes 29 23 43 5 50 37 14 755
White NH No 29 25 41 5 47 41 12 2,723
GENERATION BY GENDER
White NH Millennial men 25 17 55 4 47 40 13 1,750
White NH Millennial women 25 27 43 5 42 45 13 1,186
White NH Gen Xer men 31 19 45 5 54 34 12 1,869
White NH Gen Xer women 29 30 35 5 45 44 11 1,562
White NH Boomer men 32 23 41 5 54 36 11 3,631
White NH Boomer women 29 32 34 5 45 45 11 3,569
White NH Silent men 39 20 37 4 60 31 9 1,626
White NH Silent women 36 33 26 6 49 42 10 2,076
EDUCATION 2-WAY BY GENDER
White NH College grad men 29 24 44 3 51 42 8 4,296
White NH College grad women 27 36 33 3 41 53 6 3,713
White NH Some coll or less men 31 19 45 5 54 33 13 4,748
White NH Some coll or less women 30 27 36 6 46 40 14 5,015
EDUCATION 4-WAY BY GENDER
White NH Post graduate men 25 29 43 3 46 47 7 1,698
White NH Post graduate women 21 45 32 2 33 62 5 1,460
White NH College men 32 21 44 4 54 38 8 2,598
White NH College women 31 31 34 4 46 47 7 2,253
White NH Some college men 32 17 45 5 56 33 11 2,305
White NH Some college women 31 26 38 5 49 39 12 2,625
White NH HS or less men 30 20 45 5 52 34 15 2,443
White NH HS or less women 29 29 34 7 44 41 15 2,390
MARITAL STATUS BY GENDER
White NH Married men 34 19 43 5 58 32 10 2,909
White NH Married women 34 26 36 4 52 37 10 2,406
White NH Unmarried men 23 21 52 5 44 42 13 1,802
White NH Unmarried women 23 33 39 6 37 49 14 2,239
PARENT BY GENDER
White NH Parent men 33 18 45 4 57 31 11 378
White NH Parent women 26 26 42 6 44 41 15 377
White NH Non-parent men 29 21 45 5 49 38 12 1,380
White NH Non-parent women 28 30 37 5 45 43 12 1,343
REGION
White NH Northeast 25 31 39 4 42 46 12 3,172
White NH New England (CT ME MA NH RI VT) 19 29 50 3 39 49 12 957
White NH Middle Atlantic (DE DC MD NJ NY PA) 27 33 35 5 43 46 11 2,580
White NH Midwest 28 26 40 5 47 41 12 4,594
White NH Great Lakes-East North (IN IL MI OH WI) 28 27 40 5 46 42 11 3,017
White NH Midwest-West North (IA KS MN MO NE ND SD) 30 25 41 5 48 39 13 1,577
White NH South 35 21 39 5 55 34 11 6,191
White NH South Atlantic (FL GA NC SC VA WV) 33 21 41 5 54 35 11 3,087
White NH South Central (AL AR KY LA MS OK TN TX) 38 20 38 5 58 32 11 2,739
White NH West 29 25 41 5 46 42 11 3,866
White NH Mountain (AZ CO ID NM MT UT NV WY) 34 19 44 4 53 36 11 1,567
White NH Pacific (AK CA HI OR WA) 25 29 40 6 42 47 11 2,299
COMMUNITY TYPE
White NH Urban 25 30 41 4 42 48 10 4,955
White NH Suburban 31 24 40 5 51 38 11 9,004
White NH Rural 34 22 39 6 52 35 13 3,730
RELIGIOUS TRADITION
White NH Evangelical Protestant 46 14 34 5 68 22 9 4,814
White NH Mainline Protestant 30 26 38 6 48 40 12 4,144
White NH Catholic 31 30 36 3 50 41 10 3,435
White NH Mormon 55 10 33 2 76 16 8 410
White NH Jewish 16 47 33 4 30 62 8 478
White NH Total Unaffiliated 12 32 51 5 28 59 13 3,635
White NH Atheist 6 43 48 3 16 73 10 621
White NH Agnostic 10 37 49 4 24 67 8 724
White NH Nothing in particular 14 28 52 5 32 54 15 2,290