On Monday's Bachelor, the Ali vs. Vienna war raged on -- but the show's host Chris Harrison tells Us that the two ladies need to get over their bickering, or they'll both lose their shot at love with Jake Pavelka.

"Vienna and Ali are two of Jake's favorites, and they know that," Harrison tells "The funny thing is, as you'll see, those two are beating each other up so bad that Tenley is just skating through the door. Tenley is so sweet and maybe she doesn't outwardly show it, but I think she realizes, 'Hey, you guys keep fighting amongst yourselves!'"

Ali, Harrison adds, "has to forget about Vienna and worry about herself." He says she needs to realize, "'Enough with the bickering, enough that the cattiness. If I'm going to do this, I need to be with Jake. If Jake likes [Vienna], then so be it. I can't judge why she's here, and I just need to take care of myself.'"

Adds Harrison, "The quicker she realizes that, the better she will be."

Ali and Vienna "think that they are different, but they are really not," Harrison tells Us. "I mean, their personalities - on the surface - appear to be different, but they are really caring, loving people. It's funny because they think, if Jake likes Vienna or if Jake likes Ali, he can't possibly like me, but in actuality they don't realize how similar they are because obviously they don't get to see how they are on a date, so it's really kind of ironic. We get to see behind the curtain so we know that, but they don't."