根据显示在轴标记位置的数据对ggplot2轴标记进行着色

I have this dataset:

我有这个数据集:

top_bot_5_both <- structure(list(
  name = structure(c(20L, 19L, 18L, 17L, 16L, 15L, 14L, 13L, 12L, 
                     11L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L), 
                   .Label = c("Michele Bachmann", "Donald Trump", "Ted Cruz", 
                              "Newt Gingrich", "Rick Santorum", "Terry McAuliffe", 
                              "Nancy Pelosi", "Debbie Wasserman Schultz", 
                              "Tammy Baldwin", "Joe Biden", "Rand Paul", "Jeb Bush", 
                              "John Kasich", "Barack Obama", "Bill Clinton", 
                              "Hillary Clinton", "Nathan Deal", "Tim Kaine", 
                              "Rob Portman", "Sherrod Brown"), 
                   class = "factor"),
  Party = c("Democratic", "Republican", "Democratic", "Republican", "Democratic", 
            "Democratic", "Democratic", "Republican", "Republican", "Republican", 
            "Republican", "Republican", "Republican", "Republican", "Republican", 
            "Democratic", "Democratic", "Democratic", "Democratic", "Democratic"), 
  total_ratings = c(35L, 48L, 51L, 49L, 296L, 41L, 599L, 64L, 80L, 55L, 
                    61L, 472L, 123L, 82L, 61L, 31L, 35L, 48L, 33L, 75L), 
  sum = c(22, 29, 21, 18, 96, 12, 172, 16, 18, 2, -86, -525, -94, -57, 
          -42, -19, -14, -7, -4, -1), 
  score = c(0.628571428571429, 0.604166666666667, 0.411764705882353, 
            0.36734693877551, 0.324324324324324, 0.292682926829268, 
            0.287145242070117, 0.25, 0.225, 0.0363636363636364, -1.40983606557377, 
            -1.11228813559322, -0.764227642276423, -0.695121951219512, 
            -0.688524590163934, -0.612903225806452, -0.4, -0.145833333333333, 
            -0.121212121212121, -0.0133333333333333)), 
  class = c("tbl_df", "tbl", "data.frame"), 
  row.names = c(NA, -20L), 
  .Names = c("name", "Party", "total_ratings", "sum", "score"))
top_bot_5_bot