Shrink a vector from N1 down to N2 items without triggering the default constructor and using only move semantics

Could you help me with an efficient way to shrink an std::vector<T> from N1 down to N2 (N2 <= N1) items in it without requiring T to have a default constructor (i.e. resize() is not an option because it requires a default constructor because it can be used to grow also), and using only move semantics (without requiring a copy constructor/assignment operator in T)? Whether the operation actually shrinks the allocated memory is optional (I haven't yet decided which one is better for my program).

What I have tried so far:

template<typename T> void Filter(vector<T> &v) {
    // ... Filter the N1 items of the vector and move them to the first N2 positions
    vector<T>(move(v)).swap(v); // this is wrong
}