A tension rod mechanism for a tension rod having a first outer shaft with a second inner shaft slideable therein. A first collar receiveable in the first outer shaft of a tension rod for rotational movement therewith and slidable axial movement relative thereto threadingly engages a tapered first threaded shaft and is configured to apply a outwardly-directed radial force to the first outer shaft. A second collar fixedly receivable in the second inner shaft for movement therewith engages the second threaded shaft. A first rotation of the first outer shaft relative to the second inner shaft increases the outwardly-directed radial force applied by the first collar to the first outer shaft, and a second rotation in an opposite direction increases the axial distance between the first and second collars.