Why Syria Attack Is Less Popular In House Than In Senate
Currently, only 25 out of 435 House representatives have clearly stated that they're in favor of an attack while 23 out of 100 Senators have done the same. Meanwhile, 113 representatives have clearly said no compared to only 17 Senators. An additional 115 representatives are "leaning no" compared to 10 Senators.
The rest are "undecided". A majority in the House is thus currently on record as "no" or "leaning no" while only a small minority is in favor. By contrast, in the Senate, almost as many are in favor as are "no" or "leaning no".
Why is the situation so different? Basically, that is because attacking Syria is the centrist position while those who oppose an attack are right-wing Republicans or left-wing Democrats. And Senators of both parties are generally more centrist than their House colleagues.
The reason why Senators are generally more centrist than their House colleagues is because of differences in their electoral districts. Senators are elected in state-wide elections, meaning that they have to win over not just their base, but also centrist voters (centrist is however of course, centrist by that state's standards, which means something very differently in for example Oklahoma than in for example Hawaii). By contrast, House districts are usually notoriously "gerrymandered" so that certain districts are overwhelmingly Republican and other districts are overwhelmingly Democratic. As a result, a vast majority of districts are "safe" for either party.
As a result the only way most incumbents can lose is if they lose their party's primaries. This means in turn that they will have to appeal to their party's base and can ignore centrist voters, making most House Republicans a lot more conservative than most Senate Republicans and making most House Democrats a lot more liberal than most Senate Democrats.