Miller said it was a family decision -- a feeling that the goals Miller set in the early 1970s have been largely achieved and that it was time to pass on the seat and redirect his considerable energies at home.
"I just thought, you know what, be proud of this. It's been 40 years. Let's regenerate the Democracy," he said.
After four decades on Capitol Hill, from the end of Vietnam to the beginning of the Affordable Care Act, the Contra Costa congressman has decided to call it quits at the close of this year.
"In the history of the Congress, over 10,000 people who have served in the Congress, only about 15 have been there as long as me," Miller said.
Now 68-years-old, Miller eventually rose to the top echelons of the Democratic Party and became a right-hand man of sorts to Speaker Nancy Pelosi. As he looks back on his career, Miller says some of his most recent achievements on education, labor, and healthcare make him the most proud.
"Various presidents, Republicans and Democrats, tried to get national healthcare. When that passed, I really felt like mission accomplished," Miller said.
Asked what she was most proud of him for, Miller's wife Cynthia said, "His consistency, his views, and passion on the working class, on fairness and equity."
After 40 years of weekly commutes between D.C. and his home in Martinez, Miller will settle down -- but he'll continue working on the issues that motivated him from the beginning.
"I'm still driven with a purpose, with a passion, and I want to find other venues to work on the issues that I've spent my life, public life, working on," he said.
Miller would not speculate on who might succeed him, but did acknowledge that there are plenty of talented candidates. One man, California Sen. Mark Desaulnier has already announced his candidacy.