....and how they are violating the Constitution by refusing to approve any nominees...
Please show the part of the constitution which states they have to approve nominees or are required to do this according to a time frame.
Replacing a SC justice requires the president and the Senate. Some Republicans have declared they will not participate in that process.
If they go through with that, it will be unprecedented.
No, I don't think any of them said that. I think that's just your typical warped and twisted interpretation of what was said. Besides, it's not up to "some Republicans" because the nominee goes to the Senate Judiciary Committee for consideration. That's 11 Republicans and 9 Democrats. They will decide if the nominee is rejected or if the nominee moves to the floor for a vote. If the nominee moves to the floor, the Republicans can filibuster and require a super majority in order to have a vote. If there is a vote, Republicans are free to not participate in that but I don't think they would do so. And that's how the process works.
Now... Cruz has said that he will not approve any Obama justice. Some say he shouldn't have made such a bold statement without knowing who Obama would nominate but there is nothing "unprecedented" about not approving a president's nominee. Cruz is on the SJC along with Mike Lee and Jeff Sessions, so there are three votes who will probably reject anyone Obama will likely nominate. On the other hand, if the 9 Dems can get 2 Republicans to side with them, they can move the nominee to the floor and that's not unlikely. Still, they will have to overcome the filibuster to have a vote. In order to do that, a lot of Republicans are going to have to support the nominee. If it's someone like Sotomayor or Kegan, that's not going to happen. If it's someone more like a Roberts or Kennedy, perhaps it will... we'll have to see. I think there is going to be a political price to pay for Republicans who support anyone who isn't a Constitutional originalist like Scalia.