Those of you who like a side of certainty with your box office entrée may want to dine elsewhere this morning. That’s because we’re witnessing an extremely close race between Safe House and The Vow for number one. As estimates currently stand, Safe House seems to have the edge - $23.9 million to The Vow’s $23.6 million. But the real news is how none of the new President’s Day releases – including the 3D sequel Ghost Rider: Spirit of Vengeance - could threaten the holdovers in their fight for first.

Declaring a weekend winner on Sunday morning is always a risky proposition. Three-day estimates include Sunday night and, because no one can say what will happen in the future, we have to admit that our numbers may not always prove accurate. This weekend, two additional factors make the job of predicting a box office winner especially difficult: the exceptionally close race between Safe House and The Vow, and the fact that the Sunday audience may be larger than expected thanks to Monday’s national holiday. With that in mind, here’s what we know now. Tomorrow, who can say?

Universal’s action-drama Safe House earned an estimated $23.9 million in its second weekend, bringing its domestic total up to $78.2 million. The studio is projecting a four-day weekend of at least $27 million, though other studios disagree. According to Sony, the runaway romantic hit The Vow (a joint release with Screen Gems) will come out on top by Monday with over $27 million. See the problem with taking a definitive stand on this one?

No matter which film claims the President’s Day crown, no one can take away the fact that both titles have proved to be more successful than imagined. The Vow is already the most successful film in Screen Gems’ history, eclipsing the $80 million domestic total of Dear John. And Safe House is only $2 million off the pace of the 2007 Denzel Washington hit, American Gangster. With things so close, the only factor that separates the top two films is cost. The reported budget of Safe House is $120 million to The Vow’s $60 million, so even if the former takes the four-day crown, The Vow still wins.

Hopefully, Sony’s success with The Vow will temper their disappointment over Ghost Rider: Spirit of Vengeance. The 3D sequel to 2007’s comic adaptation got off to a decent start on Friday when it was within spitting distance of first place. That distance opened up by Saturday, however, and this morning it looks like the flaming biker will have to settle for third. The original Ghost Rider grossed $115 million in the US and $228 million worldwide from a budget of $110 million. Not awful numbers for a film that is generally considered… awful. The fact that 75% of the sequel’s 3,174 locations were 3D equipped didn’t help push this weekend’s grosses close to the $30 million minimum that was needed to make a second Ghost Rider justifiable, however.  Here’s hoping international audiences still dig Nic Cage movies.

The second of this weekend’s new releases was also a bit disappointing. Fox’s This Means War was moved from its original Valentine’s Day release date in deference to weak tracking numbers and the big debut of last weekend’s The Vow.  Still, the romantic comedy with Reese Witherspoon, directed by McG, did not deliver the $20 million minimum debut expected from such a high-profile project. On a positive note, at least This Means War saw a bigger first weekend than the $7.4 million of Witherspoon’s How Do You Know back in 2010.

At first glance the third new President’s Day release looks even weaker than This Means War - but looks can be deceiving. Although The Secret World of Arrietty placed ninth with $6.3 million, that figure represents the most successful launch of a Disney/Studio Ghibli release to date and nearly doubles the first weekend of 2009’s Ponyo. Also, Arrietty has already grossed $126 million worldwide so anything the US can throw into that pot is gravy.

What would a February be without a new Tyler Perry movie?  Though next weekend will be another crowded frame at the box office, with four titles including Gone and Wanderlust debuting, Perry’s Good Deeds is the one to watch... though something tells me few of you are going to watch it.