Sen. John McCain’s return to Washington during key legislative deliberations has been curbed in part by concerns over the deadly flu season, his daughter Meghan said Wednesday.

In an interview with Politico’s “Women Rule” podcast, the Arizona Republican’s daughter said her father, recovering from chemotherapy for aggressive brain cancer and a viral infection in December, is taking precautions that are keeping him in Arizona.

“Part of the problem, too, is like it’s this deadly, crazy flu season,” said Meghan McCain, a co-host of “The View” on ABC. “And his immune system is so down, everybody is worried about him getting the flu.” This flu season could be the worst in a decade, with 12,000 confirmed hospitalizations since the fall, the Centers for Disease Control and Prevention said in a report for the week ending Jan. 20.

McCain added that her father undergoes physical therapy at his cabin outside Sedona, focusing on his mobility following a tear in each Achilles tendon.

“Mentally, he’s 100 percent there,” she said. “It’s taken some time to get back to physical fighting form.”

McCain’s absence has complicated Senate business for months in a chamber that is now divided between 51 Republicans and 49 members of the Democratic caucus.

Given the close margin, 100 percent attendance from all other senators has been mandatory for several tricky votes, including the tax overhaul in December and an upcoming two-year budget deal set for a vote Thursday that would add more than $500 billion in federal spending for military and domestic programs.

McCain’s health has not totally sidelined his work, however. He and Sen. Christopher Coons, D-Del., introduced a bill Monday that would grant permanent legal status to undocumented immigrants known as “dreamers” and start bolstering security along the U.S.-Mexico border. The proposal is aimed at satisfying both Democrats holding the line over immigration policies on one side and the White House and congressional Republicans demanding additional measures to curb the flow of undocumented migrants and narcotics on the other.

There is “a very high likelihood that he will come back to D.C. at some point,” Meghan McCain said, though he did not return in January, when his staff suggested he might. A spokeswoman for McCain did not respond to a request for comment.

McCain underwent rounds of chemotherapy and radiation to treat glioblastoma, the terminal form of brain cancer he was diagnosed with in July. McCain has been undergoing treatment since early September at the National Institutes of Health in Bethesda, Maryland.

In December, he was admitted to nearby Walter Reed National Military Medical Center for side effects of that treatment, including the viral infection.

McCain, who also serves as chairman of the Senate Armed Services Committee, has been absent during critical discussions of the defense budget. The recent review and strategy of nuclear weapons was discussed in a closed hearing on Jan. 23. The committee has also held several hearings on the readiness of defense personnel, a focus of McCain as operations continue against Islamist militants around the globe and as long-term threats from Russia and China persist.

The Washington Post’s Ed O’Keefe contributed to this report.

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