People hate congress but they tend to like their representative. Having two hundred or so random members of congress endorse a candidate of course does nothing to make them more appealing to most people. But having their member of congress endorse a candidate does. And of course, the more representatives, senators, and governors endorse a specific candidate, the more people there are who have their representative, senator, or governor endorsing that candidate, and the more that candidate is likely to appeal to the people in aggregate.