Marco Rubio really wants to hold onto his Senate seat, he swears — but it seems like Florida voters may not be so sure.

After his failed presidential bid, the Florida Republican swore up and down he'd be a "private citizen" come January 2017, right up until he reversed course and announced he'd run for re-election to the Senate. Rubio's flip-flop was largely interpreted in part as an effort to help Republicans hold onto their Senate majority, with Rubio being a strong candidate against Democratic opponent Rep. Patrick Murphy. But a new Public Policy Polling survey shows Rubio locked in a dead heat with Murphy:

Public Policy Polling surveyed 742 likely Florida voters for this poll from Oct. 25-26, and the results have a 3.6-point margin of error. But while the poll shows the two men in a dead heat, its results also hint at how either candidate can get a leg up in the race: PPP noted that undecided voters are "looking at gun violence prevention as a major factor in their upcoming vote," with 72 percent of these undecided respondents supporting background checks for all gun sales.

Rubio has said he was moved to jump back into the Senate race in part by the deadly June attack on an Orlando nightclub, where a lone gunman killed 49 people — though last December he voted against a measure that would have expanded background checks.

Rubio has also been attempting to distance himself from Donald Trump, who trails Hillary Clinton in the same PPP poll by 4 points in the Sunshine State. But Rubio has affirmed that he'll be voting for Trump, so whether Rubio's delicate dance around the Republican nominee will help or hurt him remains to be seen. The RealClearPolitics average of polls of the Rubio-Murphy race shows the incumbent hanging on to a 3.6-point lead — but it also shows Murphy has been steadily gaining support in recent weeks. The two held their second and final debate Wednesday at Broward College near Fort Lauderdale, which you can read more about at the Miami Herald. Kimberly Alters

As a whole, the United States is experiencing its most sustained and significant decline in confirmed COVID-19 infections since the virus first reached the country last year, but the situation does vary by region. On Tuesday, the question of why cases in New York City, the original U.S. epicenter, don't seem to be declining as quickly as the rest of the country.

On Monday, for instance, New York's 14-day decline in cases was just 1 percent. Compared to the 40 percent national decline over that same period, that's pretty slow. Nobody has pinpointed a singular explanation (and there likely isn't one), but there are some simple, plausible theories you've probably heard before over the last 11 months.

The most obvious one would be testing. The city government has reportedly hinted that it considers its testing program more robust than elsewhere, so it's still picking up more mild or asymptomatic cases of the virus, generally speaking, and a big drop in hospitalizations does seem to back up that notion. Meanwhile, FiveThirtyEight's Nate Silver theorized the disparity grew even more pronounced in recent weeks because bad weather limited the number of people who could access testing in many places.

New York City Mayor Bill de Blasio addressed the question himself Tuesday, arguing that his city also was starting from a high peak. Tim O'Donnell

Researchers in California are expressing concern over a COVID-19 variant in the state, which The Los Angeles Times reports appears "increasingly dangerous."

Scientists from UC San Francisco examined the B.1.427/B.1.429 COVID-19 variant spreading in California, and they say that it "not only spreads more readily than its predecessors, but also evades antibodies generated by COVID-19 vaccines or prior infection and it's associated with severe illness and death," The Los Angeles Times writes.

The researchers warned that the variant should be viewed as a "variant of concern" like others from the United Kingdom, South Africa and Brazil.

"The devil is already here," Dr. Charles Chiu, who led the new analysis, warned. "I wish it were different. But the science is the science."

The California strain reportedly appears to reduce the effect of neutralizing antibodies by a factor of two, compared to a factor of 6.2 for the South Africa strain. The study also suggests it "could have greater virulence," the Times writes, noting the researchers looked at 324 hospitalized patients' medical charts and found that those infected with the B.1.427/B.1.429 variant were more likely to be admitted to the ICU, as well as more likely to die. Still, Chiu said this could potentially be a result of hospitals being overwhelmed due to the increased transmissibility of the variant, rather than the variant itself being more deadly.

Separately, another study that hasn't yet been published pointed to a "modest, but meaningful, difference" of almost 10 percent in the chance of becoming infected if a household member has the B.1.427/B.1.429 variant versus another variant, The New York Times reports.

At the same time, cardiologist Eric Topol on Tuesday pushed back on labeling the California variant "increasingly dangerous" at this stage, noting, "there isn't even a preprint published and we're watching dramatic descent in cases, hospitalization and deaths despite its high frequency." California's and San Francisco County's public health departments are reportedly reviewing the new analysis. Brendan Morrow

There was quite a bit of finger pointing Tuesday as former security officials testified before Congress about the Jan. 6 Capitol riot.

Former Capitol Police Chief Steven Sund — who said he regrets resigning in the riot's aftermath — testified that he requested assistance from National Guard troops two days before the attack, but was shot down by former House sergeant-at-arms Paul Irving because of concerns about "optics." Irving, though, said Sund never made that request and suggested he would have ensured the National Guard's presence if he had.

The pair also offered conflicting stories from the day of the attack. Sund said he called Irving early on to request more help, but Irving says he has no memory of the call, even after reviewing his phone records.

Sund also alleged a lack of action on the part of the Pentagon, testifying that he waited hours for the department to authorize National Guard assistance during the assault. Read more at Politico. Tim O'Donnell

Pfizer/BioNTech and Moderna pledged Tuesday to boost their current distribution of COVID-19 vaccines.

As it stands, Pfizer and Moderna are distributing 4-5 million vaccine doses each week. Pfizer plans to up that to 13 million doses weekly by mid-March, and Moderna is working to distribute 40 million doses per month, the companies told the House Energy and Commerce Committee during a Tuesday hearing. Moderna plans to ship at least 100 million doses by the end of May.

The increased production promises come amid a sluggish coronavirus vaccine rollout. President Biden originally set the U.S. on a goal of distributing 100 million vaccine doses during his first 100 days in office, but increased it to 150 million as it became clear the original plan wouldn't allow the U.S. to achieve herd immunity for months. The U.S. gave out an average of 1.45 million vaccines each day in the week of Feb. 10-17, per the Centers for Disease Control and Prevention.

Both Moderna and Pfizer are currently testing booster shots that may work better against more transmissible COVID-19 variants. Moderna is testing its vaccine's efficacy on adolescents and hopes to distribute it to them by the fall. Kathryn Krawczyk

Former Sen. David Perdue (R-Ga.) won't be pursuing a 2022 Senate comeback bid after all.

Perdue, who lost his Senate seat to Sen. Jon Ossoff (D-Ga.) during Georgia's runoff elections in January, announced Tuesday that "after much prayer and reflection," he has decided not to run for Senate in Georgia in 2022.

"This is a personal decision, not a political one," Perdue said, adding that he will "do everything I can" to ensure the eventual Republican candidate wins the seat.

The former Georgia senator had been considering challenging Sen. Raphael Warnock (D-Ga.), who in 2022 would be running for a full six-year term after completing the term of Sen. Johnny Isakson (R-Ga.). In fact, Perdue recently filed paperwork to run, and a senior adviser confirmed to The Atlanta Journal-Constitution that he was "leaning heavily toward" running.

Former Sen. Kelly Loeffler (R-Ga.) and former Rep. Doug Collins (R-Ga.) have also been considering running for the Senate seat, the Atlanta Journal-Constitution noted, but they had reportedly been waiting to see what Perdue would do before making a decision. Brendan Morrow

Despite Sen. Joe Manchin's (D-W.Va.) promise to vote for his party's coronavirus relief bill, his and Sen. Kyrsten Sinema's (D-Ariz.) opposition to the package's $15 minimum wage hike may still sink it.

Progressives' long fight for a $15 federal minimum wage finally found its vehicle in the COVID-19 relief package currently being considered in the Senate. As it stands, the bill will raise the minimum wage from $7.25 to $9.50 once it's passed, and keep growing annually until it reaches $15 in 2025. But Manchin would prefer the cap to remain at $11 per hour, and Sinema doesn't think it should be in the bill at all, leaving the party at an impasse they plan to solve with help from the Senate parliamentarian, Politico reports.

The parliamentarian advises senators on the rules and procedures of the body, especially when it comes to a Reconciliation bill, which the Democrats are using to push through their relief bill without GOP support. Republicans and Democrats are planning to meet with the parliamentarian Wednesday to argue against and for the wage hike, respectively, Politico reports. The GOP says the hike will hurt small businesses struggling in the pandemic, while Manchin has argued "throwing $15 out there right now just makes it very difficult in rural America," despite the wage increase not taking full effect for years.

The impasse has Democrats considering knocking the hike to just $11 or $12/hour, Rep. John Yarmouth (D-Ky.) told Politico. Still, progressives led by Senate Budget Committee Chair Bernie Sanders (I-Vt.) are standing firm, with Sanders telling reporters on Monday that "I think we're going to pass [the bill] as it is." Kathryn Krawczyk