Plugging Rebirth on a recent morning show, Jennifer Lopez, accompanied by her usual caravan of dancers and musicians, rolled out a medley of her hits. These were the songs you either adore or loathe, the ones that pop up on nearly every NOW! or Totally Hits compilation: ''Love Don't Cost a Thing,'' ''I'm Real,'' and, buried amidst it all, a sliver of one of her first singles, ''Waiting for Tonight.'' It was effective, but perhaps not in the way Lopez intended. Leading into songs from Rebirth, the performance was a reminder of what a fine (if Madonna-lite) track ''Waiting for Tonight'' was and how her music has rarely lived up to the potential of that song.
Thanks to her incessant selfpromotion, we all know Lopez as actress, singer, clothing and sun-glasses designer, and perfumer. This wide-spectrum branding has done wonders for her portfolio but little for her music, especially on the albums following her multiplatinum-selling 1999 debut, On the 6 (home to ''Waiting for Tonight''). With each successive disc, she relentlessly strove to be all things to all people. To help her cross over to hip-hop radio, she brought in one rapper after another, making for a series of awkward. tacked-together singles. (Such cross-demographic marketing plus the way her limited vocal and dancing chops were creatively disguised with backup singers and hoofers and quickcut videos is her lasting legacy.) When she attempted ballads for the desperate-housewives crowd, she only exposed her spaghetti-thin pipes.
Starting with its title, Rebirth aims to return Lopez to her pre-J. Logo roots. Some of the On the 6 hired guns reappear, along with big-buck producers Timbaland and Rodney Jerkins. But though Lopez has wisely retreated from the ballads of This Is Me...Then (which gave us the dumb but undeniable ''Jenny From the Block,'' a genuine J. Lo guilty pleasure), something's still off.
Start with the single ''Get Right,'' which has the makings of a good track thanks to that squawking Maceo Parker sax sample but doesn't have much more to offer. The breathy valentines that dominate the disc pillow-talk banalities like ''Step Into My World'' and ''Ryde or Die'' are musically and vocally flimsy, lacking the force of great R&B. ''Cherry Pie'' is a knockoff of Prince's rock-guitar side but without the whimsy; ''I Got U'' wants to be retro-soul but doesn't approach a good Alicia Keys record. Again, Lopez recruits a rapper to concoct groan-inducing rhymes about how true she's been to her hood, yet even with Fat Joe pitching in, ''Hold You Down'' is as colorless as Lopez's voice.
There is one moment of genuine drama on Rebirth: ''(Can't Believe) This Is Me,'' produced by hubby Marc Anthony as if it were a show-stopper in a lavish Latin Broadway musical. (You can practically see the dry-ice fog as Lopez tackles the melody.) The song is a little hoary, but unlike most of what's around it, at least it makes an impression. One gets the sense from Rebirth that Lopez wants her music to be inoffensive and as easy to swallow as baby food, all the better to reach as wide a consumer base as possible. Too bad, since somewhere inside Jennifer Lopez Inc. is a dancing queen still waiting to break out, if only for tonight.