The length of each Congressman term has a strong effect on their voting decision. It is necessary to take into account that Members of the House of Representatives serve two-year terms and are considered for reelection every even year. Senators, on the other hand, serve six-year terms and elections to the Senate are staggered over even years so that only about 1/3 of the Senate is up for reelection during any election.
As a result of that, Representative Jones has little choice but to vote in favour of the bill supported by his constituents, as he would have a very little time to address the damage to his reputation that his vote would cause.
Conversely, Senator Miller has a longer term and thus, a better chance of address other issues and gain his constituents trust over again.