Updated 3:15 p.m. | It may be January, but the Senate absences for potential presidential candidates have already begun.  

Sen. Rand Paul of Kentucky opted against attending the joint House-Senate Republican Republican retreat in Pennsylvania, and now it’s been reported that Sen. Marco Rubio, R-Fla., could miss a week’s worth of business on the floor.  

ABC News reported that Rubio would spend the week fundraising, with several events in California. Rubio is among those in the Senate Republican Conference mulling a White House bid. His Senate seat is also on the ballot in 2016.  

Rubio’s office would not comment on the ABC report.  

Rubio, Paul and Sen. Ted Cruz, R-Texas, appeared Sunday evening onstage together at an event in California sponsored by Freedom Partners Chamber of Commerce, an entity backed by the Koch brothers.  

“It’s not unusual for presidential candidates to miss Senate votes,” Rubio spokesman Alex Conant said. “Senator Rubio has not made a final decision about 2016, but he’s seriously considering running for president and taking the necessary steps to prepare a competitive campaign. As he travels the country talking about his agenda to help the middle class, there will be no doubt where he stands on any important issues before the Senate.”  

Top Republican aides wouldn’t criticize Rubio for his political activities causing him to miss votes. He also has a book tour.  

Absences this week could complicate a couple of issues. For one, Monday evening’s scheduled cloture vote to limit debate on legislation approving the Keystone XL pipeline from Canada looks like it could fall short of the 60 votes needed to limit debate for a variety of reasons.  

There’s been some unease among supportive Democrats about the amendment process last week on the floor, and getting the needed 60 votes could be in jeopardy.  

“As we move forward on this bill, I hope to get votes on my amendments and many others that Senators wish to bring up so the Senate can fully debate and vote on legislation, and get to work. That’s our job and it’s what the American people want us to do,” North Dakota Democrat Heidi Heitkamp, a pipeline supporter, said in a statement issued on Friday.  

That’s despite the fact that last November, the bill was called up with no amendments, and nine Democrats still serving in the Senate voted for passage of the approval measure without such an open process.  

In any event, Rubio won’t be the only Republican senator missing some business on the Senate floor this week, as Armed Services Chairman John McCain, R-Ariz., said that he was heading to Saudi Arabia as part of a congressional delegation to pay respects following the death of King Abdullah.  

“I am now leaving in a couple hours to go to … Saudi Arabia to, as part of a delegation over the death of the, of the Saudi king, and I do have great sympathy and I’m glad I was asked, but all things considered, I’d rather be sitting there with you guys,” McCain said Monday morning on Dan Patrick’s sports talk program, which is broadcasting from Arizona this week ahead of the Super Bowl there.  

President Barack Obama, traveling in India, altered his itinerary to also go to Saudi Arabia this week.  

“The United States delegation, led by the President, is going to pay respects to the memory of King Abdullah, a longstanding partner of the United States, and also to meet with the new King, King Salman. And I think, principally, I think this is to mark this transition in leadership and to pay respects to the family and to the people of Saudi Arabia,” White House Press Secretary Josh Earnest said of that stop. “But I’m sure that while we’re there they’ll touch on some of the leading issues where we cooperate very closely with Saudi Arabia.”  

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