A cementing assembly is mounted to a lower end of a running string. The running string has an obstruction in it such as a cable preventing a wiper dart from passing through. A production string liner wiper plug is secured to the running tool with a shear pin or other device. A dart is temporarily suspended above the liner wiper plug in a manner that cement can be pumped around the dart and through an open bore in the wiper plug. Picking up to let dogs extend followed by setting down releases the dart. Picking up again exposes a lateral port to circulate out contaminated cement. Setting down closes the port and pressure launches the plug to push the cement into the annulus surrounding the string being run in. A passage without restrictions results at the top of the cemented string after the running tool is pulled out of the hole.