The tech rumor mill, which never sleeps and is ever hungry for new fodder, has cranked up with a new target in its sights -- Google's next "pure-Android" flagship phone, the Nexus 6.

While rumors of form factor, screen size and hardware specs begin to float to the surface, one overarching question has the tech world's attention -- namely, who will build the device.

It won't be Motorola, the conventional wisdom goes, because Google sold it to Chinese PC maker Lenovo for $2.9 billion.

But wait a minute: While Motorola was busy creating its own phones, the Moto X and Moto G, Google was busy selling lots of its Nexus 5 phones -- which it didn't build itself, leaving that task to South Korea's LG Electronics.

So why not a Lenovo-built Nexus 6? After all, the Motorola sale left considerable linkages between the two companies. Google now has a 6 percent interest in Lenovo, and Lenovo gets access to some -- but not all -- of the Motorola patents Google kept for itself.

Google puts its name on its Nexus phones, but has always farmed out the actual creation of the devices to someone else. Like the Nexus 5, the Nexus 4 -- also a considerable sales success for Google -- came from LG.

Taiwan's HTC built the first Nexus phone for Google, the Nexus One, while South Korea's Samsung built the next two, the Nexus S and the Galaxy Nexus, before LG received the blessing from on high -- well, from Google's Mountain View, Calif., headquarters -- to carry on the Nexus generations.

And most betting -- or at least most rumors -- have tagged the Nexus 6, whenever it arrives, as another LG effort.

That rumors have been strengthened by LG's announcement of its next smartphone that will carry its own name, the LG G Pro 2, which could easily morph into the Nexus 6.

That was the case with the LG G2, which with a few differences was more or less a twin of the Nexus 5, something noted by many tech watchers when both showed up on the market.

If the G Pro 2 is in fact LG's trial run at a Nexus 6, the Google unit could feature an octa-core 2.4Ghz processor or even 3Ghz, 4 GB of RAM, a 5-inch display, a 3,100 mAh battery, and storage options of 64 GB and 128 GB.

A fingerprint security sensor, currently all the rage, could also show up.

Still, LG is not a shoo-in as the anointed Nexus 6 maker. If Google goes with Lenovo, it could reach millions of new customers in China and other developing Asian markets.

Three manufacturers have built Nexus phones for Google, proof the search giant has no qualms about looking for a company that's the best fit at the time of the debut of the next generation of its flagship device.

So: LG? Lenovo? A return to Samsung or HTC? Or some dark horse ready to jump on the Google Nexus train?

Until rumors solidify into silicon, it's anybody's bet.