I would like to know how partisan my Senators are. I have found various partisan rankings, but I am actually looking for a statistic of the % of time my Senators vote along party lines.
DW Nominate scores do exactly that. The closer to 1 the score is, the more your Senator votes with other conservatives. The closer to -1 the score is, the more your Senator votes with other liberals. Congress has been becoming more and more polarized since the 1980s, though Republicans at a rate several times faster than Democrats. If your Senator is a Republican and not John McCain, he probably votes consistently with other Republicans.
Our unique ideology analysis assigns a score to Members of Congress according to their legislative behavior by how similar the pattern of bills and resolutions they cosponsor are to other Members of Congress. The score can be interpreted as a conservative—liberal scale, although of course it only takes into account a small aspect of reality.
ALL SENATORS most conservative
1 1.00 Sen. James “Jim” Inhofe [R-OK]
2 0.99 Sen. Pat Roberts [R-KS]
... EXPAND ...
99 0.06 Sen. Bernard “Bernie” Sanders [I-VT]
100 0.00 Sen. Alan “Al” Franken [D-MN, 2009-2017] most liberal
If we click EXPAND, the midlist Senators show a few Democrats rated more conservative than some Republicans:
44 0.74 Sen. Benjamin Sasse [R-NE]
45 0.74 Sen. John McCain [R-AZ,1987-2018]
46 0.73 Sen. Richard Burr [R-NC]
47 0.72 Sen. Joe Manchin [D-WV]
48 0.71 Sen. Joe Donnelly [D-IN]
49 0.69 Sen. Richard Shelby [R-AL]
50 0.68 Sen. Bob Corker [R-TN]
51 0.67 Sen. Lamar Alexander [R-TN]
52 0.67 Sen. Lisa Murkowski [R-AK]
53 0.61 Sen. Robert “Rob” Portman [R-OH]
54 0.59 Sen. Bill Nelson [D-FL]
55 0.58 Sen. Heidi Heitkamp [D-ND]
56 0.57 Sen. Jon Tester [D-MT]
57 0.51 Sen. Angus King [I-ME]
58 0.51 Sen. Susan Collins [R-ME]
59 0.50 Sen. Claire McCaskill [D-MO]