Let’s start with the math. The 435-member House of Representatives passes laws by majority vote, which means that at least 218 members of the lower house must vote in favor of a bill in order for it to be approved.
In the 100-member Senate, the situation is more complicated. A group of senators can obstruct, or prevent the proposal from being put to a vote if 60 senators do not agree that it is time to stop debating the measure and take a vote.
When there are enough votes to end the obstruction, the Senate must still take a formal vote to pass the bill, but it requires a simple majority. If the bill is not controversial and none of the senators use obstruction, a majority vote is enough to approve it.
The president wants the Senate to get rid of the right to obstruction and move to a 51 percent majority to pass any proposal in the Senate. Otherwise, he says, few bills will pass. Donald Ritchie, historian emeritus of the U.S. Senate, predicts that senators are unlikely to change the rule allowing obstruction.
Once upon a time, during obstruction, senators would speak from the floor all night to prevent a vote. In recent years, it was enough for senators to simply threaten obstruction for the upper chamber leadership to back down.
Obstruction has a broader purpose than preventing the passage of specific legislation. It promotes the Senate’s tendency to seek bipartisan compromise. It makes the Senate a very different body from the House, where for the past 20 years the majority party has traditionally focused on legislation it can pass without the help of the other political party.
Once the Senate and House of Representatives pass their own bills on a particular issue, the process of reconciling the two different versions begins. If the resulting compromise version is approved in both the House and Senate (they vote again), the bill is then sent to the president.
However, House and Senate rules are not the only factor. The president and the courts also play an important role. They are based on the system of checks and balances of the U.S. Constitution, which exist to ensure that one branch of government does not have too much influence.
When a bill is approved by Congress, it goes to the White House, where its month-long or year-long journey may end with the president’s pen stroke.
If the president rejects or vetoes legislation, it does not necessarily mean the end of the bill. Congress can override a presidential veto by a two-thirds vote in both houses. This “restraint” prevents the president from blocking legislation when it has broad support.