BAGHDAD — Vice President Cheney said yesterday that “we’ve got a long way to go” in reducing violence in Iraq in a trip punctuated by an explosion that shook windows at the U.S. Embassy, where Mr. Cheney was visiting.

The vice president urged that Iraq’s parliament abandon plans for a two-month summer vacation while American forces are fighting. With important issues pending, including how to share Iraq’s oil wealth, “any undue delay would be difficult to explain,” Mr. Cheney said.

As Democrats clamor for an end to the four-year-old war and President Bush sags in the polls, the White House is under intense political pressure to show that Prime Minister al-Maliki’s government is making progress. Mr. Cheney urged Iraq’s leaders to do more to reduce violence and promote political reconciliation.

Eight days after Mr. Bush vetoed a bill setting deadlines for U.S. troop withdrawals from Iraq, the White House also served notice that Mr. Bush would veto a follow-up bill drafted by House Democratic leaders that would pay for the Iraq war only into summer. At the same time, Defense Secretary Gates held out hope that troops can begin withdrawing if the Iraqi government makes progress by fall.

During Mr. Cheney’s visit, a truck bomb exploded in midtown Irbil in the semi-autonomous region of Kurdistan yesterday, killing 19 people, injuring 70, and illustrating the worsening violence in areas of Iraq previously considered to be relatively safe.