The Obama administration and its allies are making a last-minute push to persuade Americans to enroll in health insurance under the Affordable Care Act.Open enrollment ends at midnight Monday, and with it, the chance to avoid a penalty for not purchasing insurance in 2014, which people will pay with their federal-income taxes next year.Administration officials say interest is surging as the deadline nears. Sunday evening, Health and Human Services announced 2 million visits over the weekend to HealthCare.gov, the federal government's enrollment site.In the last week alone, the call center handled a record 2.5 million calls, surpassing the 2.4 million it received during the entire month of February.Over the weekend, HHS Secretary Kathleen Sebelius appeared at a Baptist church in Miami to urge Floridians to sign up before the deadline. She plans a fresh round of television interviews with local stations Monday to boost enrollment numbers.An interview with Vice President Biden encouraging young people to enroll will air Monday on celebrity chef Rachael Ray's talk show."The traffic and energy and interest this weekend shows many more are interested in the coverage," White House spokeswoman Tara McGuinness said Sunday afternoon.Republicans saw the situation differently.In an op-ed appearing in Monday's editions of USA TODAY, Sen. Tom Coburn, R-Okla., said the vast majority of enrollees were previously insured. Getting Americans to "re-enroll in insurance is no great achievement," he said, "particularly when many of those customers were forced to give up plans they liked."Sen. John Barrosso, R-Wyo., said the administration is "cooking the books" on enrollment figures. The real test "is what kind of insurance will those people actually have," he said during an appearance on Fox News Sunday.Those who start the process - either by working on a paper application with a navigator, attempting to enroll online, or talking with a call center representative - may continue the process after the deadline passes.The government has boosted the number of call center representatives, as well as the capacity of the website, to handle the increased volume. Even so, officials with the federal government's health-care exchange tweeted Sunday afternoon: "High call center volume right now. System will now allow consumers to leave their info to be contacted later when we can serve them."

MIAMI, FL - JANUARY 15: As people stand in line to speak with an insurance agent Dailem Delombard sits with an agent from Sunshine Life and Health Advisors as she tries to purchase health insurance under the Affordable Care Act at the kiosk setup at the Mall of Americas on January 15, 2014 in Miami, Florida. Today is deadline day for those that want insurance to start on February the 1st. According to the owner of Sunshine Life and Health Advisors, Odalys Arevalo, their business selling insurance under the Affordable Care Act has exploded so much so that by the end of the week they will be moving to a 24,000 square foot space at the mall because they have outgrown the kiosk. They have over 25 agents and are seeing hundreds of people daily, last Saturday they saw about 1,000 people with wait times of over 5 hours. (Photo by Joe Raedle/Getty Images)

Joe Raedle