As mentioned earlier, petitions were handed in to recall state Senator Angela Giron. Petitioners need 11,285 signatures and they handed in 13500 signatures. Here's some details on Colorado and the recall and the questions on the resignation possibility.
The signature total may point to a verification fight down the line. Two points to this: The rule of thumb is that petitioners need about 15% more signatures to safely survive a challenge. So, the petitioners here are just over the line. But, it could get a little more complicated when it is a high-profile recall -- perhaps the signatures get a closer look by a high-powered legal team.
The other point is that different states appear to have stricter signature checking method than others. I've noted that Arizona seems to have a very strict standard, one that has resulted in 40% of signatures rejected in some cases. Wisconsin, due to its law, has a very lenient standard.
If the recall does get on the ballot, we may see two state legislative recalls occur at once. On the local level, multi-official recalls in one election are a common occurrence. As you see in this link, multi-official recalls frequently result in a clean sweep, one way or the other (either all sides winning or all sides losing).
On the state level, we've seen multi-official recalls happen numerous times in the past -- North Dakota (1921) Idaho (1971), Michigan (1983) and Wisconsin (2011, 2012). Additionally, California has three recalls in 1995, though all were on different days. In North Dakota, Idaho and Michigan, the officials were all kicked out of office. In Wisconsin, while the explanation is a little more complex, there was a split in both 2011 and 2012.