Jennifer Steinhauer

Distrust between Congress and Obama and a Republican allergy to almost any increased federal spending have combined into a contentious brew that led this week to the unraveling of a basic appropriations bill, an unsettled fight over funding to combat the Zika virus and a dim horizon for once-promising items like an overhaul of criminal justice laws.

As the Republican candidates for the White House battled in Wisconsin last week, House Speaker Paul D. Ryan was conspicuously absent from his home state — but he was very much on the political stage.

Responding to a drug crisis that has contributed to more American deaths than car crashes, the Senate on Thursday overwhelmingly passed a broad drug treatment and prevention bill, the largest of its kind since a law in 2008 that mandated insurance coverage for addiction treatment.

Panicked Republicans question whether Donald Trump will be able to unite the Republican-controlled Congress that would normally be expected to promote and promulgate his agenda, an internal crisis nearly unheard-of in a generation of American politics.

President Barack Obama on Tuesday challenged Republicans to offer a plausible rationale for refusing to consider a Supreme Court candidate to replace Justice Antonin Scalia, and he pledged to nominate someone with an “outstanding legal mind” who cares about democracy and the rule of law.

House Speaker Paul D. Ryan has ordered the House majority leader and the chairman of the House Foreign Affairs Committee to begin talking to members about the feasibility of a measure that would authorize war against the Islamic State militant group.

As its opening move in the newly convened Congress, the House voted Wednesday to repeal the Affordable Care Act, the 62nd such vote but the first time that a bill will make it to President Barack Obama’s desk.

Rep. Paul D. Ryan said Thursday that he would seek to replace John A. Boehner as House speaker after two factions of the House Republicans — one small and moderate, one mainstream and large — endorsed him, bringing him close to securing the speaker’s gavel he had never wanted to seek.

Giving hope to House Republicans who have been besieged by conflict and chaos, Rep. Paul D. Ryan said Tuesday that he would be willing to serve as speaker if all the factions of his party could unite behind him.

After more than a decade of wrenching national debate over the intrusiveness of government intelligence agencies, a bipartisan wave of support has gathered to sharply limit the federal government’s sweeps of phone and Internet records.

Several Senate Republicans on Tuesday came out publicly against filibustering the first major gun control legislation since 1993 before it is even brought up for debate on the Senate floor, as advocates inched toward breaking a conservative blockade of the measure.

In the 90 years since Rebecca Felton of Georgia became the first woman in the U.S. Senate -- sworn in for a mere 24 hours -- women remain an anomaly in the upper chamber. But with 20 female senators now in office, an all-time high, women have morphed from the curiosity they were for much of the 20th century into an important new force on key committees and legislation.