The address, known as the Queen’s Speech, reflected the different set of political obstacles that Mr. Cameron will face in his second term. Plans for a British bill of rights that would limit the reach of European laws on human rights were mentioned in terms that suggest they are likely to be delayed. And there were no details about how he would put in place one of his central pledges: a reduction of around 12 billion pounds, or about $18.5 billion, in welfare spending. Before the election, Mr. Cameron also promised not to increase income tax, the value-added tax — the main sales tax — or social security payments known as national insurance, although that still gives him some leeway to raise other taxes.

Now that he is able to govern without the support of other parties, Mr. Cameron is in a position he almost certainly never expected, and his election promises were made under the assumption that he would have to bargain and compromise as part of a coalition government.

During his first term in power, Mr. Cameron had to negotiate with his junior coalition partner, the Liberal Democrats, about which measures would be put into law. Although that constrained him, it also provided him with an excuse to soft-pedal issues that were either a lower priority or more politically complex.

Now, Mr. Cameron will be unable to point to outside pressures when he is reluctant to back measures championed by the right wing of his Conservative Party.

Yet his parliamentary majority is slim, just 12 votes, which carries other risks. As a young political adviser, Mr. Cameron worked for the government of the last Conservative Party prime minister, John Major, who was elected in 1992 with a majority of 21 seats. That quickly melted away, leaving the prime minister with steadily dwindling authority until he was ejected from power in 1997.