Mouse move object along x axis

I want my object to move with the mouse only on the x-axis because the object is getting affected by another force along the y-axis. The code I currently have moves it along both.

 function Update () { 
 
      var mousePos = Input.mousePosition; 
 
      var wantedPos = Camera.main.ScreenToWorldPoint (Vector3 (mousePos.x, mousePos.y, 10)); 
 
      transform.position = wantedPos; 
 
 }

How can I have the mouse move it along the x axis without affecting what happens to the y-axis