  We propose a solution to the longstanding cosmological constant (CC) problem
which is based on the fusion of two existing concepts. The first is the
suggestion that the proper description of classical gravitational effects is
the gauge theory of gravity in which the connection instead of the metric acts
as the dynamical variable. The resulting field equation does not then contain
the CC term. This removes the connection between the CC and the quantum vacuum
energy, and therefore addresses the {\it old} CC problem of why quantum vacuum
energy does not gravitate. The CC-equivalent in this approach arises from the
constant of integration when reducing the field equation to the Einstein
equation. The second is the assumption that the universe obeys de Sitter
symmetry, with the observed accelerating expansion as its manifestation. We
combine these ideas and identify the constant of integration with the
inverse-square of the radius of curvature of the de Sitter space. The origin of
dark energy (DE) is therefore associated with the inherent spacetime geometry,
with the smallness of DE protected by symmetry. This addresses the {\it new} CC
problem, or the DE puzzle. This approach, however, faces major challenges from
quantum considerations. These are the ghost problem associated with higher
order gravity theories and the quantum instability of the de Sitter spacetime.
We discuss their possible remedies.
